Provided by: zfsutils-linux_0.8.3-1ubuntu12.17_amd64 
NAME
zfs — configures ZFS file systems
SYNOPSIS
zfs -?V
zfs create [-p] [-o property=value]... filesystem
zfs create [-ps] [-b blocksize] [-o property=value]... -V size volume
zfs destroy [-Rfnprv] filesystem|volume
zfs destroy [-Rdnprv] filesystem|volume@snap[%snap[,snap[%snap]]]...
zfs destroy filesystem|volume#bookmark
zfs snapshot [-r] [-o property=value]... filesystem@snapname|volume@snapname...
zfs rollback [-Rfr] snapshot
zfs clone [-p] [-o property=value]... snapshot filesystem|volume
zfs promote clone-filesystem
zfs rename [-f] filesystem|volume|snapshot filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
zfs rename -r snapshot snapshot
zfs list [-r|-d depth] [-Hp] [-o property[,property]...] [-s property]... [-S property]...
[-t type[,type]...] [filesystem|volume|snapshot]...
zfs set property=value [property=value]... filesystem|volume|snapshot...
zfs get [-r|-d depth] [-Hp] [-o field[,field]...] [-s source[,source]...] [-t
type[,type]...] all | property[,property]... [filesystem|volume|snapshot|bookmark]...
zfs inherit [-rS] property filesystem|volume|snapshot...
zfs upgrade
zfs upgrade -v
zfs upgrade [-r] [-V version] -a | filesystem
zfs userspace [-Hinp] [-o field[,field]...] [-s field]... [-S field]... [-t type[,type]...]
filesystem|snapshot
zfs groupspace [-Hinp] [-o field[,field]...] [-s field]... [-S field]... [-t type[,type]...]
filesystem|snapshot
zfs projectspace [-Hp] [-o field[,field]...] [-s field]... [-S field]... filesystem|snapshot
zfs project [-d|-r] file|directory...
zfs project -C [-kr] file|directory...
zfs project -c [-0] [-d|-r] [-p id] file|directory...
zfs project [-p id] [-rs] file|directory...
zfs mount
zfs mount [-Olv] [-o options] -a | filesystem
zfs unmount [-f] -a | filesystem|mountpoint
zfs share -a | filesystem
zfs unshare -a | filesystem|mountpoint
zfs bookmark snapshot bookmark
zfs send [-DLPRbcehnpvw] [[-I|-i] snapshot] snapshot
zfs send [-LPcenvw] [-i snapshot|bookmark] filesystem|volume|snapshot
zfs send [-Penv] -t receive_resume_token
zfs receive [-Fhnsuv] [-o origin=snapshot] [-o property=value] [-x property]
filesystem|volume|snapshot
zfs receive [-Fhnsuv] [-d|-e] [-o origin=snapshot] [-o property=value] [-x property]
filesystem
zfs receive -A filesystem|volume
zfs allow filesystem|volume
zfs allow [-dglu] user|group[,user|group]... perm|@setname[,perm|@setname]...
filesystem|volume
zfs allow [-dl] -e|everyone perm|@setname[,perm|@setname]... filesystem|volume
zfs allow -c perm|@setname[,perm|@setname]... filesystem|volume
zfs allow -s @setname perm|@setname[,perm|@setname]... filesystem|volume
zfs unallow [-dglru] user|group[,user|group]... [perm|@setname[,perm|@setname]...]
filesystem|volume
zfs unallow [-dlr] -e|everyone [perm|@setname[,perm|@setname]...] filesystem|volume
zfs unallow [-r] -c [perm|@setname[,perm|@setname]...] filesystem|volume
zfs unallow [-r] -s -@setname [perm|@setname[,perm|@setname]...] filesystem|volume
zfs hold [-r] tag snapshot...
zfs holds [-rH] snapshot...
zfs release [-r] tag snapshot...
zfs diff [-FHt] snapshot snapshot|filesystem
zfs program [-jn] [-t instruction-limit] [-m memory-limit] pool script [--] arg1 ...
zfs load-key [-nr] [-L keylocation] -a | filesystem
zfs unload-key [-r] -a | filesystem
zfs change-key [-l] [-o keylocation=value] [-o keyformat=value] [-o pbkdf2iters=value]
filesystem
zfs change-key -i [-l] filesystem
zfs version
DESCRIPTION
The zfs command configures ZFS datasets within a ZFS storage pool, as described in zpool(8).
A dataset is identified by a unique path within the ZFS namespace. For example:
pool/{filesystem,volume,snapshot}
where the maximum length of a dataset name is MAXNAMELEN (256 bytes) and the maximum amount
of nesting allowed in a path is 50 levels deep.
A dataset can be one of the following:
file system A ZFS dataset of type filesystem can be mounted within the standard system
namespace and behaves like other file systems. While ZFS file systems are
designed to be POSIX compliant, known issues exist that prevent compliance in
some cases. Applications that depend on standards conformance might fail due
to non-standard behavior when checking file system free space.
volume A logical volume exported as a raw or block device. This type of dataset
should only be used when a block device is required. File systems are
typically used in most environments.
snapshot A read-only version of a file system or volume at a given point in time. It is
specified as filesystem@name or volume@name.
bookmark Much like a snapshot, but without the hold on on-disk data. It can be used as
the source of a send (but not for a receive). It is specified as
filesystem#name or volume#name.
ZFS File System Hierarchy
A ZFS storage pool is a logical collection of devices that provide space for datasets. A
storage pool is also the root of the ZFS file system hierarchy.
The root of the pool can be accessed as a file system, such as mounting and unmounting,
taking snapshots, and setting properties. The physical storage characteristics, however,
are managed by the zpool(8) command.
See zpool(8) for more information on creating and administering pools.
Snapshots
A snapshot is a read-only copy of a file system or volume. Snapshots can be created
extremely quickly, and initially consume no additional space within the pool. As data
within the active dataset changes, the snapshot consumes more data than would otherwise be
shared with the active dataset.
Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back,
visibility is determined by the snapdev property of the parent volume.
File system snapshots can be accessed under the .zfs/snapshot directory in the root of the
file system. Snapshots are automatically mounted on demand and may be unmounted at regular
intervals. The visibility of the .zfs directory can be controlled by the snapdir property.
Bookmarks
A bookmark is like a snapshot, a read-only copy of a file system or volume. Bookmarks can
be created extremely quickly, compared to snapshots, and they consume no additional space
within the pool. Bookmarks can also have arbitrary names, much like snapshots.
Unlike snapshots, bookmarks can not be accessed through the filesystem in any way. From a
storage standpoint a bookmark just provides a way to reference when a snapshot was created
as a distinct object. Bookmarks are initially tied to a snapshot, not the filesystem or
volume, and they will survive if the snapshot itself is destroyed. Since they are very light
weight there's little incentive to destroy them.
Clones
A clone is a writable volume or file system whose initial contents are the same as another
dataset. As with snapshots, creating a clone is nearly instantaneous, and initially
consumes no additional space.
Clones can only be created from a snapshot. When a snapshot is cloned, it creates an
implicit dependency between the parent and child. Even though the clone is created
somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long
as a clone exists. The origin property exposes this dependency, and the destroy command
lists any such dependencies, if they exist.
The clone parent-child dependency relationship can be reversed by using the promote
subcommand. This causes the "origin" file system to become a clone of the specified file
system, which makes it possible to destroy the file system that the clone was created from.
Mount Points
Creating a ZFS file system is a simple operation, so the number of file systems per system
is likely to be numerous. To cope with this, ZFS automatically manages mounting and
unmounting file systems without the need to edit the /etc/fstab file. All automatically
managed file systems are mounted by ZFS at boot time.
By default, file systems are mounted under /path, where path is the name of the file system
in the ZFS namespace. Directories are created and destroyed as needed.
A file system can also have a mount point set in the mountpoint property. This directory is
created as needed, and ZFS automatically mounts the file system when the zfs mount -a
command is invoked (without editing /etc/fstab). The mountpoint property can be inherited,
so if pool/home has a mount point of /export/stuff, then pool/home/user automatically
inherits a mount point of /export/stuff/user.
A file system mountpoint property of none prevents the file system from being mounted.
If needed, ZFS file systems can also be managed with traditional tools (mount, umount,
/etc/fstab). If a file system's mount point is set to legacy, ZFS makes no attempt to
manage the file system, and the administrator is responsible for mounting and unmounting the
file system. Because pools must be imported before a legacy mount can succeed,
administrators should ensure that legacy mounts are only attempted after the zpool import
process finishes at boot time. For example, on machines using systemd, the mount option
x-systemd.requires=zfs-import.target
will ensure that the zfs-import completes before systemd attempts mounting the filesystem.
See systemd.mount(5) for details.
Deduplication
Deduplication is the process for removing redundant data at the block level, reducing the
total amount of data stored. If a file system has the dedup property enabled, duplicate data
blocks are removed synchronously. The result is that only unique data is stored and common
components are shared among files.
Deduplicating data is a very resource-intensive operation. It is generally recommended that
you have at least 1.25 GiB of RAM per 1 TiB of storage when you enable deduplication.
Calculating the exact requirement depends heavily on the type of data stored in the pool.
Enabling deduplication on an improperly-designed system can result in performance issues
(slow IO and administrative operations). It can potentially lead to problems importing a
pool due to memory exhaustion. Deduplication can consume significant processing power (CPU)
and memory as well as generate additional disk IO.
Before creating a pool with deduplication enabled, ensure that you have planned your
hardware requirements appropriately and implemented appropriate recovery practices, such as
regular backups. As an alternative to deduplication consider using compression=on, as a less
resource-intensive alternative.
Native Properties
Properties are divided into two types, native properties and user-defined (or "user")
properties. Native properties either export internal statistics or control ZFS behavior.
In addition, native properties are either editable or read-only. User properties have no
effect on ZFS behavior, but you can use them to annotate datasets in a way that is
meaningful in your environment. For more information about user properties, see the User
Properties section, below.
Every dataset has a set of properties that export statistics about the dataset as well as
control various behaviors. Properties are inherited from the parent unless overridden by
the child. Some properties apply only to certain types of datasets (file systems, volumes,
or snapshots).
The values of numeric properties can be specified using human-readable suffixes (for
example, k, KB, M, Gb, and so forth, up to Z for zettabyte). The following are all valid
(and equal) specifications: 1536M, 1.5g, 1.50GB.
The values of non-numeric properties are case sensitive and must be lowercase, except for
mountpoint, sharenfs, and sharesmb.
The following native properties consist of read-only statistics about the dataset. These
properties can be neither set, nor inherited. Native properties apply to all dataset types
unless otherwise noted.
available The amount of space available to the dataset and all its children,
assuming that there is no other activity in the pool. Because space
is shared within a pool, availability can be limited by any number of
factors, including physical pool size, quotas, reservations, or other
datasets within the pool.
This property can also be referred to by its shortened column name,
avail.
compressratio For non-snapshots, the compression ratio achieved for the used space
of this dataset, expressed as a multiplier. The used property
includes descendant datasets, and, for clones, does not include the
space shared with the origin snapshot. For snapshots, the
compressratio is the same as the refcompressratio property.
Compression can be turned on by running: zfs set compression=on
dataset. The default value is off.
createtxg The transaction group (txg) in which the dataset was created.
Bookmarks have the same createtxg as the snapshot they are initially
tied to. This property is suitable for ordering a list of snapshots,
e.g. for incremental send and receive.
creation The time this dataset was created.
clones For snapshots, this property is a comma-separated list of filesystems
or volumes which are clones of this snapshot. The clones' origin
property is this snapshot. If the clones property is not empty, then
this snapshot can not be destroyed (even with the -r or -f options).
The roles of origin and clone can be swapped by promoting the clone
with the zfs promote command.
defer_destroy This property is on if the snapshot has been marked for deferred
destroy by using the zfs destroy -d command. Otherwise, the property
is off.
encryptionroot For encrypted datasets, indicates where the dataset is currently
inheriting its encryption key from. Loading or unloading a key for the
encryptionroot will implicitly load / unload the key for any
inheriting datasets (see zfs load-key and zfs unload-key for details).
Clones will always share an encryption key with their origin. See the
Encryption section for details.
filesystem_count The total number of filesystems and volumes that exist under this
location in the dataset tree. This value is only available when a
filesystem_limit has been set somewhere in the tree under which the
dataset resides.
keystatus Indicates if an encryption key is currently loaded into ZFS. The
possible values are none, available, and unavailable. See zfs
load-key and zfs unload-key.
guid The 64 bit GUID of this dataset or bookmark which does not change over
its entire lifetime. When a snapshot is sent to another pool, the
received snapshot has the same GUID. Thus, the guid is suitable to
identify a snapshot across pools.
logicalreferenced The amount of space that is "logically" accessible by this dataset.
See the referenced property. The logical space ignores the effect of
the compression and copies properties, giving a quantity closer to the
amount of data that applications see. However, it does include space
consumed by metadata.
This property can also be referred to by its shortened column name,
lrefer.
logicalused The amount of space that is "logically" consumed by this dataset and
all its descendents. See the used property. The logical space
ignores the effect of the compression and copies properties, giving a
quantity closer to the amount of data that applications see. However,
it does include space consumed by metadata.
This property can also be referred to by its shortened column name,
lused.
mounted For file systems, indicates whether the file system is currently
mounted. This property can be either yes or no.
objsetid A unique identifier for this dataset within the pool. Unlike the
dataset's guid , the objsetid of a dataset is not transferred to other
pools when the snapshot is copied with a send/receive operation. The
objsetid can be reused (for a new datatset) after the dataset is
deleted.
origin For cloned file systems or volumes, the snapshot from which the clone
was created. See also the clones property.
receive_resume_token For filesystems or volumes which have saved partially-completed state
from zfs receive -s, this opaque token can be provided to zfs send -t
to resume and complete the zfs receive.
referenced The amount of data that is accessible by this dataset, which may or
may not be shared with other datasets in the pool. When a snapshot or
clone is created, it initially references the same amount of space as
the file system or snapshot it was created from, since its contents
are identical.
This property can also be referred to by its shortened column name,
refer.
refcompressratio The compression ratio achieved for the referenced space of this
dataset, expressed as a multiplier. See also the compressratio
property.
snapshot_count The total number of snapshots that exist under this location in the
dataset tree. This value is only available when a snapshot_limit has
been set somewhere in the tree under which the dataset resides.
type The type of dataset: filesystem, volume, or snapshot.
used The amount of space consumed by this dataset and all its descendents.
This is the value that is checked against this dataset's quota and
reservation. The space used does not include this dataset's
reservation, but does take into account the reservations of any
descendent datasets. The amount of space that a dataset consumes from
its parent, as well as the amount of space that is freed if this
dataset is recursively destroyed, is the greater of its space used and
its reservation.
The used space of a snapshot (see the Snapshots section) is space that
is referenced exclusively by this snapshot. If this snapshot is
destroyed, the amount of used space will be freed. Space that is
shared by multiple snapshots isn't accounted for in this metric. When
a snapshot is destroyed, space that was previously shared with this
snapshot can become unique to snapshots adjacent to it, thus changing
the used space of those snapshots. The used space of the latest
snapshot can also be affected by changes in the file system. Note
that the used space of a snapshot is a subset of the written space of
the snapshot.
The amount of space used, available, or referenced does not take into
account pending changes. Pending changes are generally accounted for
within a few seconds. Committing a change to a disk using fsync(2) or
O_SYNC does not necessarily guarantee that the space usage information
is updated immediately.
usedby* The usedby* properties decompose the used properties into the various
reasons that space is used. Specifically, used = usedbychildren +
usedbydataset + usedbyrefreservation + usedbysnapshots. These
properties are only available for datasets created on zpool "version
13" pools.
usedbychildren The amount of space used by children of this dataset, which would be
freed if all the dataset's children were destroyed.
usedbydataset The amount of space used by this dataset itself, which would be freed
if the dataset were destroyed (after first removing any refreservation
and destroying any necessary snapshots or descendents).
usedbyrefreservation The amount of space used by a refreservation set on this dataset,
which would be freed if the refreservation was removed.
usedbysnapshots The amount of space consumed by snapshots of this dataset. In
particular, it is the amount of space that would be freed if all of
this dataset's snapshots were destroyed. Note that this is not simply
the sum of the snapshots' used properties because space can be shared
by multiple snapshots.
userused@user The amount of space consumed by the specified user in this dataset.
Space is charged to the owner of each file, as displayed by ls -l.
The amount of space charged is displayed by du and ls -s. See the zfs
userspace subcommand for more information.
Unprivileged users can access only their own space usage. The root
user, or a user who has been granted the userused privilege with zfs
allow, can access everyone's usage.
The userused@... properties are not displayed by zfs get all. The
user's name must be appended after the @ symbol, using one of the
following forms:
• POSIX name (for example, joe)
• POSIX numeric ID (for example, 789)
• SID name (for example, joe.smith@mydomain)
• SID numeric ID (for example, S-1-123-456-789)
Files created on Linux always have POSIX owners.
userobjused@user The userobjused property is similar to userused but instead it counts
the number of objects consumed by a user. This property counts all
objects allocated on behalf of the user, it may differ from the
results of system tools such as df -i.
When the property xattr=on is set on a file system additional objects
will be created per-file to store extended attributes. These
additional objects are reflected in the userobjused value and are
counted against the user's userobjquota. When a file system is
configured to use xattr=sa no additional internal objects are normally
required.
userrefs This property is set to the number of user holds on this snapshot.
User holds are set by using the zfs hold command.
groupused@group The amount of space consumed by the specified group in this dataset.
Space is charged to the group of each file, as displayed by ls -l.
See the userused@user property for more information.
Unprivileged users can only access their own groups' space usage. The
root user, or a user who has been granted the groupused privilege with
zfs allow, can access all groups' usage.
groupobjused@group The number of objects consumed by the specified group in this dataset.
Multiple objects may be charged to the group for each file when
extended attributes are in use. See the userobjused@user property for
more information.
Unprivileged users can only access their own groups' space usage. The
root user, or a user who has been granted the groupobjused privilege
with zfs allow, can access all groups' usage.
projectused@project The amount of space consumed by the specified project in this dataset.
Project is identified via the project identifier (ID) that is object-
based numeral attribute. An object can inherit the project ID from its
parent object (if the parent has the flag of inherit project ID that
can be set and changed via chattr -/+P or zfs project -s) when being
created. The privileged user can set and change object's project ID
via chattr -p or zfs project -s anytime. Space is charged to the
project of each file, as displayed by lsattr -p or zfs project. See
the userused@user property for more information.
The root user, or a user who has been granted the projectused
privilege with zfs allow, can access all projects' usage.
projectobjused@project
The projectobjused is similar to projectused but instead it counts the
number of objects consumed by project. When the property xattr=on is
set on a fileset, ZFS will create additional objects per-file to store
extended attributes. These additional objects are reflected in the
projectobjused value and are counted against the project's
projectobjquota. When a filesystem is configured to use xattr=sa no
additional internal objects are required. See the userobjused@user
property for more information.
The root user, or a user who has been granted the projectobjused
privilege with zfs allow, can access all projects' objects usage.
volblocksize For volumes, specifies the block size of the volume. The blocksize
cannot be changed once the volume has been written, so it should be
set at volume creation time. The default blocksize for volumes is 8
Kbytes. Any power of 2 from 512 bytes to 128 Kbytes is valid.
This property can also be referred to by its shortened column name,
volblock.
written The amount of space referenced by this dataset, that was written since
the previous snapshot (i.e. that is not referenced by the previous
snapshot).
written@snapshot The amount of referenced space written to this dataset since the
specified snapshot. This is the space that is referenced by this
dataset but was not referenced by the specified snapshot.
The snapshot may be specified as a short snapshot name (just the part
after the @), in which case it will be interpreted as a snapshot in
the same filesystem as this dataset. The snapshot may be a full
snapshot name (filesystem@snapshot), which for clones may be a
snapshot in the origin's filesystem (or the origin of the origin's
filesystem, etc.)
The following native properties can be used to change the behavior of a ZFS dataset.
aclinherit=discard|noallow|restricted|passthrough|passthrough-x
Controls how ACEs are inherited when files and directories are created.
discard does not inherit any ACEs.
noallow only inherits inheritable ACEs that specify "deny" permissions.
restricted default, removes the write_acl and write_owner permissions when the ACE is
inherited.
passthrough inherits all inheritable ACEs without any modifications.
passthrough-x same meaning as passthrough, except that the owner@, group@, and everyone@
ACEs inherit the execute permission only if the file creation mode also
requests the execute bit.
When the property value is set to passthrough, files are created with a mode determined by
the inheritable ACEs. If no inheritable ACEs exist that affect the mode, then the mode is
set in accordance to the requested mode from the application.
The aclinherit property does not apply to POSIX ACLs.
acltype=off|noacl|posixacl
Controls whether ACLs are enabled and if so what type of ACL to use.
off default, when a file system has the acltype property set to off then ACLs are
disabled.
noacl an alias for off
posixacl indicates POSIX ACLs should be used. POSIX ACLs are specific to Linux and are
not functional on other platforms. POSIX ACLs are stored as an extended
attribute and therefore will not overwrite any existing NFSv4 ACLs which may be
set.
To obtain the best performance when setting posixacl users are strongly encouraged to set
the xattr=sa property. This will result in the POSIX ACL being stored more efficiently on
disk. But as a consequence, all new extended attributes will only be accessible from
OpenZFS implementations which support the xattr=sa property. See the xattr property for
more details.
atime=on|off
Controls whether the access time for files is updated when they are read. Turning this
property off avoids producing write traffic when reading files and can result in
significant performance gains, though it might confuse mailers and other similar
utilities. The values on and off are equivalent to the atime and noatime mount options.
The default value is on. See also relatime below.
canmount=on|off|noauto
If this property is set to off, the file system cannot be mounted, and is ignored by zfs
mount -a. Setting this property to off is similar to setting the mountpoint property to
none, except that the dataset still has a normal mountpoint property, which can be
inherited. Setting this property to off allows datasets to be used solely as a mechanism
to inherit properties. One example of setting canmount=off is to have two datasets with
the same mountpoint, so that the children of both datasets appear in the same directory,
but might have different inherited characteristics.
When set to noauto, a dataset can only be mounted and unmounted explicitly. The dataset
is not mounted automatically when the dataset is created or imported, nor is it mounted by
the zfs mount -a command or unmounted by the zfs unmount -a command.
This property is not inherited.
checksum=on|off|fletcher2|fletcher4|sha256|noparity|sha512|skein|edonr
Controls the checksum used to verify data integrity. The default value is on, which
automatically selects an appropriate algorithm (currently, fletcher4, but this may change
in future releases). The value off disables integrity checking on user data. The value
noparity not only disables integrity but also disables maintaining parity for user data.
This setting is used internally by a dump device residing on a RAID-Z pool and should not
be used by any other dataset. Disabling checksums is NOT a recommended practice.
The sha512, skein, and edonr checksum algorithms require enabling the appropriate features
on the pool. These pool features are not supported by GRUB and must not be used on the
pool if GRUB needs to access the pool (e.g. for /boot).
Please see zpool-features(5) for more information on these algorithms.
Changing this property affects only newly-written data.
compression=on|off|gzip|gzip-N|lz4|lzjb|zle
Controls the compression algorithm used for this dataset.
Setting compression to on indicates that the current default compression algorithm should
be used. The default balances compression and decompression speed, with compression ratio
and is expected to work well on a wide variety of workloads. Unlike all other settings
for this property, on does not select a fixed compression type. As new compression
algorithms are added to ZFS and enabled on a pool, the default compression algorithm may
change. The current default compression algorithm is either lzjb or, if the lz4_compress
feature is enabled, lz4.
The lz4 compression algorithm is a high-performance replacement for the lzjb algorithm.
It features significantly faster compression and decompression, as well as a moderately
higher compression ratio than lzjb, but can only be used on pools with the lz4_compress
feature set to enabled. See zpool-features(5) for details on ZFS feature flags and the
lz4_compress feature.
The lzjb compression algorithm is optimized for performance while providing decent data
compression.
The gzip compression algorithm uses the same compression as the gzip(1) command. You can
specify the gzip level by using the value gzip-N, where N is an integer from 1 (fastest)
to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6 (which is also the
default for gzip(1)).
The zle compression algorithm compresses runs of zeros.
This property can also be referred to by its shortened column name compress. Changing
this property affects only newly-written data.
When any setting except off is selected, compression will explicitly check for blocks
consisting of only zeroes (the NUL byte). When a zero-filled block is detected, it is
stored as a hole and not compressed using the indicated compression algorithm.
Any block being compressed must be no larger than 7/8 of its original size after
compression, otherwise the compression will not be considered worthwhile and the block
saved uncompressed. Note that when the logical block is less than 8 times the disk sector
size this effectively reduces the necessary compression ratio; for example 8k blocks on
disks with 4k disk sectors must compress to 1/2 or less of their original size.
context=none|SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for all files in the file system under a mount point
for that file system. See selinux(8) for more information.
fscontext=none|SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for the file system file system being mounted. See
selinux(8) for more information.
defcontext=none|SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux default context for unlabeled files. See selinux(8) for more
information.
rootcontext=none|SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for the root inode of the file system. See selinux(8)
for more information.
copies=1|2|3
Controls the number of copies of data stored for this dataset. These copies are in
addition to any redundancy provided by the pool, for example, mirroring or RAID-Z. The
copies are stored on different disks, if possible. The space used by multiple copies is
charged to the associated file and dataset, changing the used property and counting
against quotas and reservations.
Changing this property only affects newly-written data. Therefore, set this property at
file system creation time by using the -o copies=N option.
Remember that ZFS will not import a pool with a missing top-level vdev. Do NOT create, for
example a two-disk striped pool and set copies=2 on some datasets thinking you have setup
redundancy for them. When a disk fails you will not be able to import the pool and will
have lost all of your data.
Encrypted datasets may not have copies=3 since the implementation stores some encryption
metadata where the third copy would normally be.
devices=on|off
Controls whether device nodes can be opened on this file system. The default value is on.
The values on and off are equivalent to the dev and nodev mount options.
dedup=off|on|verify|sha256[,verify]|sha512[,verify]|skein[,verify]|edonr,verify
Configures deduplication for a dataset. The default value is off. The default
deduplication checksum is sha256 (this may change in the future). When dedup is enabled,
the checksum defined here overrides the checksum property. Setting the value to verify has
the same effect as the setting sha256,verify.
If set to verify, ZFS will do a byte-to-byte comparsion in case of two blocks having the
same signature to make sure the block contents are identical. Specifying verify is
mandatory for the edonr algorithm.
Unless necessary, deduplication should NOT be enabled on a system. See Deduplication
above.
dnodesize=legacy|auto|1k|2k|4k|8k|16k
Specifies a compatibility mode or literal value for the size of dnodes in the file system.
The default value is legacy. Setting this property to a value other than legacy requires
the large_dnode pool feature to be enabled.
Consider setting dnodesize to auto if the dataset uses the xattr=sa property setting and
the workload makes heavy use of extended attributes. This may be applicable to SELinux-
enabled systems, Lustre servers, and Samba servers, for example. Literal values are
supported for cases where the optimal size is known in advance and for performance
testing.
Leave dnodesize set to legacy if you need to receive a send stream of this dataset on a
pool that doesn't enable the large_dnode feature, or if you need to import this pool on a
system that doesn't support the large_dnode feature.
This property can also be referred to by its shortened column name, dnsize.
encryption=off|on|aes-128-ccm|aes-192-ccm|aes-256-ccm|aes-128-gcm|aes-192-gcm|aes-256-gcm
Controls the encryption cipher suite (block cipher, key length, and mode) used for this
dataset. Requires the encryption feature to be enabled on the pool. Requires a keyformat
to be set at dataset creation time.
Selecting encryption=on when creating a dataset indicates that the default encryption
suite will be selected, which is currently aes-256-ccm. In order to provide consistent
data protection, encryption must be specified at dataset creation time and it cannot be
changed afterwards.
For more details and caveats about encryption see the Encryption section.
keyformat=raw|hex|passphrase
Controls what format the user's encryption key will be provided as. This property is only
set when the dataset is encrypted.
Raw keys and hex keys must be 32 bytes long (regardless of the chosen encryption suite)
and must be randomly generated. A raw key can be generated with the following command:
# dd if=/dev/urandom of=/path/to/output/key bs=32 count=1
Passphrases must be between 8 and 512 bytes long and will be processed through PBKDF2
before being used (see the pbkdf2iters property). Even though the encryption suite cannot
be changed after dataset creation, the keyformat can be with zfs change-key.
keylocation=prompt|file://</absolute/file/path>
Controls where the user's encryption key will be loaded from by default for commands such
as zfs load-key and zfs mount -l. This property is only set for encrypted datasets which
are encryption roots. If unspecified, the default is prompt.
Even though the encryption suite cannot be changed after dataset creation, the keylocation
can be with either zfs set or zfs change-key. If prompt is selected ZFS will ask for the
key at the command prompt when it is required to access the encrypted data (see zfs
load-key for details). This setting will also allow the key to be passed in via STDIN, but
users should be careful not to place keys which should be kept secret on the command line.
If a file URI is selected, the key will be loaded from the specified absolute file path.
pbkdf2iters=iterations
Controls the number of PBKDF2 iterations that a passphrase encryption key should be run
through when processing it into an encryption key. This property is only defined when
encryption is enabled and a keyformat of passphrase is selected. The goal of PBKDF2 is to
significantly increase the computational difficulty needed to brute force a user's
passphrase. This is accomplished by forcing the attacker to run each passphrase through a
computationally expensive hashing function many times before they arrive at the resulting
key. A user who actually knows the passphrase will only have to pay this cost once. As
CPUs become better at processing, this number should be raised to ensure that a brute
force attack is still not possible. The current default is 350000 and the minimum is
100000. This property may be changed with zfs change-key.
exec=on|off
Controls whether processes can be executed from within this file system. The default
value is on. The values on and off are equivalent to the exec and noexec mount options.
filesystem_limit=count|none
Limits the number of filesystems and volumes that can exist under this point in the
dataset tree. The limit is not enforced if the user is allowed to change the limit.
Setting a filesystem_limit to on a descendent of a filesystem that already has a
filesystem_limit does not override the ancestor's filesystem_limit, but rather imposes an
additional limit. This feature must be enabled to be used (see zpool-features(5)).
special_small_blocks=size
This value represents the threshold block size for including small file blocks into the
special allocation class. Blocks smaller than or equal to this value will be assigned to
the special allocation class while greater blocks will be assigned to the regular class.
Valid values are zero or a power of two from 512B up to 1M. The default size is 0 which
means no small file blocks will be allocated in the special class.
Before setting this property, a special class vdev must be added to the pool. See zpool(8)
for more details on the special allocation class.
mountpoint=path|none|legacy
Controls the mount point used for this file system. See the Mount Points section for more
information on how this property is used.
When the mountpoint property is changed for a file system, the file system and any
children that inherit the mount point are unmounted. If the new value is legacy, then
they remain unmounted. Otherwise, they are automatically remounted in the new location if
the property was previously legacy or none, or if they were mounted before the property
was changed. In addition, any shared file systems are unshared and shared in the new
location.
nbmand=on|off
Controls whether the file system should be mounted with nbmand (Non Blocking mandatory
locks). This is used for SMB clients. Changes to this property only take effect when the
file system is umounted and remounted. See mount(8) for more information on nbmand
mounts. This property is not used on Linux.
overlay=off|on
Allow mounting on a busy directory or a directory which already contains files or
directories. This is the default mount behavior for Linux file systems. For consistency
with OpenZFS on other platforms overlay mounts are off by default. Set to on to enable
overlay mounts.
primarycache=all|none|metadata
Controls what is cached in the primary cache (ARC). If this property is set to all, then
both user data and metadata is cached. If this property is set to none, then neither user
data nor metadata is cached. If this property is set to metadata, then only metadata is
cached. The default value is all.
quota=size|none
Limits the amount of space a dataset and its descendents can consume. This property
enforces a hard limit on the amount of space used. This includes all space consumed by
descendents, including file systems and snapshots. Setting a quota on a descendent of a
dataset that already has a quota does not override the ancestor's quota, but rather
imposes an additional limit.
Quotas cannot be set on volumes, as the volsize property acts as an implicit quota.
snapshot_limit=count|none
Limits the number of snapshots that can be created on a dataset and its descendents.
Setting a snapshot_limit on a descendent of a dataset that already has a snapshot_limit
does not override the ancestor's snapshot_limit, but rather imposes an additional limit.
The limit is not enforced if the user is allowed to change the limit. For example, this
means that recursive snapshots taken from the global zone are counted against each
delegated dataset within a zone. This feature must be enabled to be used (see
zpool-features(5)).
userquota@user=size|none
Limits the amount of space consumed by the specified user. User space consumption is
identified by the userspace@user property.
Enforcement of user quotas may be delayed by several seconds. This delay means that a
user might exceed their quota before the system notices that they are over quota and
begins to refuse additional writes with the EDQUOT error message. See the zfs userspace
subcommand for more information.
Unprivileged users can only access their own groups' space usage. The root user, or a
user who has been granted the userquota privilege with zfs allow, can get and set
everyone's quota.
This property is not available on volumes, on file systems before version 4, or on pools
before version 15. The userquota@... properties are not displayed by zfs get all. The
user's name must be appended after the @ symbol, using one of the following forms:
• POSIX name (for example, joe)
• POSIX numeric ID (for example, 789)
• SID name (for example, joe.smith@mydomain)
• SID numeric ID (for example, S-1-123-456-789)
Files created on Linux always have POSIX owners.
userobjquota@user=size|none
The userobjquota is similar to userquota but it limits the number of objects a user can
create. Please refer to userobjused for more information about how objects are counted.
groupquota@group=size|none
Limits the amount of space consumed by the specified group. Group space consumption is
identified by the groupused@group property.
Unprivileged users can access only their own groups' space usage. The root user, or a
user who has been granted the groupquota privilege with zfs allow, can get and set all
groups' quotas.
groupobjquota@group=size|none
The groupobjquota is similar to groupquota but it limits number of objects a group can
consume. Please refer to userobjused for more information about how objects are counted.
projectquota@project=size|none
Limits the amount of space consumed by the specified project. Project space consumption is
identified by the projectused@project property. Please refer to projectused for more
information about how project is identified and set/changed.
The root user, or a user who has been granted the projectquota privilege with zfs allow,
can access all projects' quota.
projectobjquota@project=size|none
The projectobjquota is similar to projectquota but it limits number of objects a project
can consume. Please refer to userobjused for more information about how objects are
counted.
readonly=on|off
Controls whether this dataset can be modified. The default value is off. The values on
and off are equivalent to the ro and rw mount options.
This property can also be referred to by its shortened column name, rdonly.
recordsize=size
Specifies a suggested block size for files in the file system. This property is designed
solely for use with database workloads that access files in fixed-size records. ZFS
automatically tunes block sizes according to internal algorithms optimized for typical
access patterns.
For databases that create very large files but access them in small random chunks, these
algorithms may be suboptimal. Specifying a recordsize greater than or equal to the record
size of the database can result in significant performance gains. Use of this property
for general purpose file systems is strongly discouraged, and may adversely affect
performance.
The size specified must be a power of two greater than or equal to 512 and less than or
equal to 128 Kbytes. If the large_blocks feature is enabled on the pool, the size may be
up to 1 Mbyte. See zpool-features(5) for details on ZFS feature flags.
Changing the file system's recordsize affects only files created afterward; existing files
are unaffected.
This property can also be referred to by its shortened column name, recsize.
redundant_metadata=all|most
Controls what types of metadata are stored redundantly. ZFS stores an extra copy of
metadata, so that if a single block is corrupted, the amount of user data lost is limited.
This extra copy is in addition to any redundancy provided at the pool level (e.g. by
mirroring or RAID-Z), and is in addition to an extra copy specified by the copies property
(up to a total of 3 copies). For example if the pool is mirrored, copies=2, and
redundant_metadata=most, then ZFS stores 6 copies of most metadata, and 4 copies of data
and some metadata.
When set to all, ZFS stores an extra copy of all metadata. If a single on-disk block is
corrupt, at worst a single block of user data (which is recordsize bytes long) can be
lost.
When set to most, ZFS stores an extra copy of most types of metadata. This can improve
performance of random writes, because less metadata must be written. In practice, at
worst about 100 blocks (of recordsize bytes each) of user data can be lost if a single on-
disk block is corrupt. The exact behavior of which metadata blocks are stored redundantly
may change in future releases.
The default value is all.
refquota=size|none
Limits the amount of space a dataset can consume. This property enforces a hard limit on
the amount of space used. This hard limit does not include space used by descendents,
including file systems and snapshots.
refreservation=size|none|auto
The minimum amount of space guaranteed to a dataset, not including its descendents. When
the amount of space used is below this value, the dataset is treated as if it were taking
up the amount of space specified by refreservation. The refreservation reservation is
accounted for in the parent datasets' space used, and counts against the parent datasets'
quotas and reservations.
If refreservation is set, a snapshot is only allowed if there is enough free pool space
outside of this reservation to accommodate the current number of "referenced" bytes in the
dataset.
If refreservation is set to auto, a volume is thick provisioned (or "not sparse").
refreservation=auto is only supported on volumes. See volsize in the Native Properties
section for more information about sparse volumes.
This property can also be referred to by its shortened column name, refreserv.
relatime=on|off
Controls the manner in which the access time is updated when atime=on is set. Turning this
property on causes the access time to be updated relative to the modify or change time.
Access time is only updated if the previous access time was earlier than the current
modify or change time or if the existing access time hasn't been updated within the past
24 hours. The default value is off. The values on and off are equivalent to the relatime
and norelatime mount options.
reservation=size|none
The minimum amount of space guaranteed to a dataset and its descendants. When the amount
of space used is below this value, the dataset is treated as if it were taking up the
amount of space specified by its reservation. Reservations are accounted for in the
parent datasets' space used, and count against the parent datasets' quotas and
reservations.
This property can also be referred to by its shortened column name, reserv.
secondarycache=all|none|metadata
Controls what is cached in the secondary cache (L2ARC). If this property is set to all,
then both user data and metadata is cached. If this property is set to none, then neither
user data nor metadata is cached. If this property is set to metadata, then only metadata
is cached. The default value is all.
setuid=on|off
Controls whether the setuid bit is respected for the file system. The default value is
on. The values on and off are equivalent to the suid and nosuid mount options.
sharesmb=on|off|opts
Controls whether the file system is shared by using Samba USERSHARES and what options are
to be used. Otherwise, the file system is automatically shared and unshared with the zfs
share and zfs unshare commands. If the property is set to on, the net(8) command is
invoked to create a USERSHARE.
Because SMB shares requires a resource name, a unique resource name is constructed from
the dataset name. The constructed name is a copy of the dataset name except that the
characters in the dataset name, which would be invalid in the resource name, are replaced
with underscore (_) characters. Linux does not currently support additional options which
might be available on Solaris.
If the sharesmb property is set to off, the file systems are unshared.
The share is created with the ACL (Access Control List) "Everyone:F" ("F" stands for "full
permissions", ie. read and write permissions) and no guest access (which means Samba must
be able to authenticate a real user, system passwd/shadow, LDAP or smbpasswd based) by
default. This means that any additional access control (disallow specific user specific
access etc) must be done on the underlying file system.
sharenfs=on|off|opts
Controls whether the file system is shared via NFS, and what options are to be used. A
file system with a sharenfs property of off is managed with the exportfs(8) command and
entries in the /etc/exports file. Otherwise, the file system is automatically shared and
unshared with the zfs share and zfs unshare commands. If the property is set to on, the
dataset is shared using the default options:
sec=sys,rw,crossmnt,no_subtree_check
See exports(5) for the meaning of the default options. Otherwise, the exportfs(8) command
is invoked with options equivalent to the contents of this property.
When the sharenfs property is changed for a dataset, the dataset and any children
inheriting the property are re-shared with the new options, only if the property was
previously off, or if they were shared before the property was changed. If the new
property is off, the file systems are unshared.
logbias=latency|throughput
Provide a hint to ZFS about handling of synchronous requests in this dataset. If logbias
is set to latency (the default), ZFS will use pool log devices (if configured) to handle
the requests at low latency. If logbias is set to throughput, ZFS will not use configured
pool log devices. ZFS will instead optimize synchronous operations for global pool
throughput and efficient use of resources.
snapdev=hidden|visible
Controls whether the volume snapshot devices under /dev/zvol/<pool> are hidden or visible.
The default value is hidden.
snapdir=hidden|visible
Controls whether the .zfs directory is hidden or visible in the root of the file system as
discussed in the Snapshots section. The default value is hidden.
sync=standard|always|disabled
Controls the behavior of synchronous requests (e.g. fsync, O_DSYNC). standard is the
POSIX specified behavior of ensuring all synchronous requests are written to stable
storage and all devices are flushed to ensure data is not cached by device controllers
(this is the default). always causes every file system transaction to be written and
flushed before its system call returns. This has a large performance penalty. disabled
disables synchronous requests. File system transactions are only committed to stable
storage periodically. This option will give the highest performance. However, it is very
dangerous as ZFS would be ignoring the synchronous transaction demands of applications
such as databases or NFS. Administrators should only use this option when the risks are
understood.
version=N|current
The on-disk version of this file system, which is independent of the pool version. This
property can only be set to later supported versions. See the zfs upgrade command.
volsize=size
For volumes, specifies the logical size of the volume. By default, creating a volume
establishes a reservation of equal size. For storage pools with a version number of 9 or
higher, a refreservation is set instead. Any changes to volsize are reflected in an
equivalent change to the reservation (or refreservation). The volsize can only be set to
a multiple of volblocksize, and cannot be zero.
The reservation is kept equal to the volume's logical size to prevent unexpected behavior
for consumers. Without the reservation, the volume could run out of space, resulting in
undefined behavior or data corruption, depending on how the volume is used. These effects
can also occur when the volume size is changed while it is in use (particularly when
shrinking the size). Extreme care should be used when adjusting the volume size.
Though not recommended, a "sparse volume" (also known as "thin provisioned") can be
created by specifying the -s option to the zfs create -V command, or by changing the value
of the refreservation property (or reservation property on pool version 8 or earlier)
after the volume has been created. A "sparse volume" is a volume where the value of
refreservation is less than the size of the volume plus the space required to store its
metadata. Consequently, writes to a sparse volume can fail with ENOSPC when the pool is
low on space. For a sparse volume, changes to volsize are not reflected in the
refreservation. A volume that is not sparse is said to be "thick provisioned". A sparse
volume can become thick provisioned by setting refreservation to auto.
volmode=default | full | geom | dev | none
This property specifies how volumes should be exposed to the OS. Setting it to full
exposes volumes as fully fledged block devices, providing maximal functionality. The value
geom is just an alias for full and is kept for compatibility. Setting it to dev hides its
partitions. Volumes with property set to none are not exposed outside ZFS, but can be
snapshoted, cloned, replicated, etc, that can be suitable for backup purposes. Value
default means that volumes exposition is controlled by system-wide tunable zvol_volmode,
where full, dev and none are encoded as 1, 2 and 3 respectively. The default values is
full.
vscan=on|off
Controls whether regular files should be scanned for viruses when a file is opened and
closed. In addition to enabling this property, the virus scan service must also be
enabled for virus scanning to occur. The default value is off. This property is not used
on Linux.
xattr=on|off|sa
Controls whether extended attributes are enabled for this file system. Two styles of
extended attributes are supported either directory based or system attribute based.
The default value of on enables directory based extended attributes. This style of
extended attribute imposes no practical limit on either the size or number of attributes
which can be set on a file. Although under Linux the getxattr(2) and setxattr(2) system
calls limit the maximum size to 64K. This is the most compatible style of extended
attribute and is supported by all OpenZFS implementations.
System attribute based xattrs can be enabled by setting the value to sa. The key
advantage of this type of xattr is improved performance. Storing extended attributes as
system attributes significantly decreases the amount of disk IO required. Up to 64K of
data may be stored per-file in the space reserved for system attributes. If there is not
enough space available for an extended attribute then it will be automatically written as
a directory based xattr. System attribute based extended attributes are not accessible on
platforms which do not support the xattr=sa feature.
The use of system attribute based xattrs is strongly encouraged for users of SELinux or
POSIX ACLs. Both of these features heavily rely of extended attributes and benefit
significantly from the reduced access time.
The values on and off are equivalent to the xattr and noxattr mount options.
zoned=on|off
Controls whether the dataset is managed from a non-global zone. Zones are a Solaris
feature and are not relevant on Linux. The default value is off.
The following three properties cannot be changed after the file system is created, and
therefore, should be set when the file system is created. If the properties are not set
with the zfs create or zpool create commands, these properties are inherited from the parent
dataset. If the parent dataset lacks these properties due to having been created prior to
these features being supported, the new file system will have the default values for these
properties.
casesensitivity=sensitive|insensitive|mixed
Indicates whether the file name matching algorithm used by the file system should be case-
sensitive, case-insensitive, or allow a combination of both styles of matching. The
default value for the casesensitivity property is sensitive. Traditionally, UNIX and
POSIX file systems have case-sensitive file names.
The mixed value for the casesensitivity property indicates that the file system can
support requests for both case-sensitive and case-insensitive matching behavior.
Currently, case-insensitive matching behavior on a file system that supports mixed
behavior is limited to the SMB server product. For more information about the mixed value
behavior, see the "ZFS Administration Guide".
normalization=none|formC|formD|formKC|formKD
Indicates whether the file system should perform a unicode normalization of file names
whenever two file names are compared, and which normalization algorithm should be used.
File names are always stored unmodified, names are normalized as part of any comparison
process. If this property is set to a legal value other than none, and the utf8only
property was left unspecified, the utf8only property is automatically set to on. The
default value of the normalization property is none. This property cannot be changed
after the file system is created.
utf8only=on|off
Indicates whether the file system should reject file names that include characters that
are not present in the UTF-8 character code set. If this property is explicitly set to
off, the normalization property must either not be explicitly set or be set to none. The
default value for the utf8only property is off. This property cannot be changed after the
file system is created.
The casesensitivity, normalization, and utf8only properties are also new permissions that
can be assigned to non-privileged users by using the ZFS delegated administration feature.
Temporary Mount Point Properties
When a file system is mounted, either through mount(8) for legacy mounts or the zfs mount
command for normal file systems, its mount options are set according to its properties. The
correlation between properties and mount options is as follows:
PROPERTY MOUNT OPTION
atime atime/noatime
canmount auto/noauto
devices dev/nodev
exec exec/noexec
readonly ro/rw
relatime relatime/norelatime
setuid suid/nosuid
xattr xattr/noxattr
In addition, these options can be set on a per-mount basis using the -o option, without
affecting the property that is stored on disk. The values specified on the command line
override the values stored in the dataset. The nosuid option is an alias for
nodevices,nosetuid. These properties are reported as "temporary" by the zfs get command.
If the properties are changed while the dataset is mounted, the new setting overrides any
temporary settings.
User Properties
In addition to the standard native properties, ZFS supports arbitrary user properties. User
properties have no effect on ZFS behavior, but applications or administrators can use them
to annotate datasets (file systems, volumes, and snapshots).
User property names must contain a colon (":") character to distinguish them from native
properties. They may contain lowercase letters, numbers, and the following punctuation
characters: colon (":"), dash ("-"), period ("."), and underscore ("_"). The expected
convention is that the property name is divided into two portions such as module:property,
but this namespace is not enforced by ZFS. User property names can be at most 256
characters, and cannot begin with a dash ("-").
When making programmatic use of user properties, it is strongly suggested to use a reversed
DNS domain name for the module component of property names to reduce the chance that two
independently-developed packages use the same property name for different purposes.
The values of user properties are arbitrary strings, are always inherited, and are never
validated. All of the commands that operate on properties (zfs list, zfs get, zfs set, and
so forth) can be used to manipulate both native properties and user properties. Use the zfs
inherit command to clear a user property. If the property is not defined in any parent
dataset, it is removed entirely. Property values are limited to 8192 bytes.
ZFS Volumes as Swap
ZFS volumes may be used as swap devices. After creating the volume with the zfs create -V
command set up and enable the swap area using the mkswap(8) and swapon(8) commands. Do not
swap to a file on a ZFS file system. A ZFS swap file configuration is not supported.
Encryption
Enabling the encryption feature allows for the creation of encrypted filesystems and
volumes. ZFS will encrypt file and zvol data, file attributes, ACLs, permission bits,
directory listings, FUID mappings, and userused / groupused data. ZFS will not encrypt
metadata related to the pool structure, including dataset and snapshot names, dataset
hierarchy, properties, file size, file holes, and deduplication tables (though the
deduplicated data itself is encrypted).
Key rotation is managed by ZFS. Changing the user's key (e.g. a passphrase) does not
require re-encrypting the entire dataset. Datasets can be scrubbed, resilvered, renamed,
and deleted without the encryption keys being loaded (see the zfs load-key subcommand for
more info on key loading).
Creating an encrypted dataset requires specifying the encryption and keyformat properties at
creation time, along with an optional keylocation and pbkdf2iters. After entering an
encryption key, the created dataset will become an encryption root. Any descendant datasets
will inherit their encryption key from the encryption root by default, meaning that loading,
unloading, or changing the key for the encryption root will implicitly do the same for all
inheriting datasets. If this inheritance is not desired, simply supply a keyformat when
creating the child dataset or use zfs change-key to break an existing relationship, creating
a new encryption root on the child. Note that the child's keyformat may match that of the
parent while still creating a new encryption root, and that changing the encryption property
alone does not create a new encryption root; this would simply use a different cipher suite
with the same key as its encryption root. The one exception is that clones will always use
their origin's encryption key. As a result of this exception, some encryption-related
properties (namely keystatus, keyformat, keylocation, and pbkdf2iters) do not inherit like
other ZFS properties and instead use the value determined by their encryption root.
Encryption root inheritance can be tracked via the read-only encryptionroot property.
Encryption changes the behavior of a few ZFS operations. Encryption is applied after
compression so compression ratios are preserved. Normally checksums in ZFS are 256 bits
long, but for encrypted data the checksum is 128 bits of the user-chosen checksum and 128
bits of MAC from the encryption suite, which provides additional protection against
maliciously altered data. Deduplication is still possible with encryption enabled but for
security, datasets will only dedup against themselves, their snapshots, and their clones.
There are a few limitations on encrypted datasets. Encrypted data cannot be embedded via the
embedded_data feature. Encrypted datasets may not have copies=3 since the implementation
stores some encryption metadata where the third copy would normally be. Since compression is
applied before encryption datasets may be vulnerable to a CRIME-like attack if applications
accessing the data allow for it. Deduplication with encryption will leak information about
which blocks are equivalent in a dataset and will incur an extra CPU cost per block written.
SUBCOMMANDS
All subcommands that modify state are logged persistently to the pool in their original
form.
zfs -?
Displays a help message.
zfs -V, --version
An alias for the zfs version subcommand.
zfs create [-p] [-o property=value]... filesystem
Creates a new ZFS file system. The file system is automatically mounted according to the
mountpoint property inherited from the parent.
-o property=value
Sets the specified property as if the command zfs set property=value was invoked at
the same time the dataset was created. Any editable ZFS property can also be set at
creation time. Multiple -o options can be specified. An error results if the same
property is specified in multiple -o options.
-p Creates all the non-existing parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent. Any property specified on the command line using the -o option is ignored.
If the target filesystem already exists, the operation completes successfully.
zfs create [-ps] [-b blocksize] [-o property=value]... -V size volume
Creates a volume of the given size. The volume is exported as a block device in
/dev/zvol/path, where path is the name of the volume in the ZFS namespace. The size
represents the logical size as exported by the device. By default, a reservation of equal
size is created.
size is automatically rounded up to the nearest 128 Kbytes to ensure that the volume has
an integral number of blocks regardless of blocksize.
-b blocksize
Equivalent to -o volblocksize=blocksize. If this option is specified in conjunction
with -o volblocksize, the resulting behavior is undefined.
-o property=value
Sets the specified property as if the zfs set property=value command was invoked at
the same time the dataset was created. Any editable ZFS property can also be set at
creation time. Multiple -o options can be specified. An error results if the same
property is specified in multiple -o options.
-p Creates all the non-existing parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent. Any property specified on the command line using the -o option is ignored.
If the target filesystem already exists, the operation completes successfully.
-s Creates a sparse volume with no reservation. See volsize in the Native Properties
section for more information about sparse volumes.
zfs destroy [-Rfnprv] filesystem|volume
Destroys the given dataset. By default, the command unshares any file systems that are
currently shared, unmounts any file systems that are currently mounted, and refuses to
destroy a dataset that has active dependents (children or clones).
-R Recursively destroy all dependents, including cloned file systems outside the target
hierarchy.
-f Force an unmount of any file systems using the unmount -f command. This option has no
effect on non-file systems or unmounted file systems.
-n Do a dry-run ("No-op") deletion. No data will be deleted. This is useful in
conjunction with the -v or -p flags to determine what data would be deleted.
-p Print machine-parsable verbose information about the deleted data.
-r Recursively destroy all children.
-v Print verbose information about the deleted data.
Extreme care should be taken when applying either the -r or the -R options, as they can
destroy large portions of a pool and cause unexpected behavior for mounted file systems in
use.
zfs destroy [-Rdnprv] filesystem|volume@snap[%snap[,snap[%snap]]]...
The given snapshots are destroyed immediately if and only if the zfs destroy command
without the -d option would have destroyed it. Such immediate destruction would occur,
for example, if the snapshot had no clones and the user-initiated reference count were
zero.
If a snapshot does not qualify for immediate destruction, it is marked for deferred
deletion. In this state, it exists as a usable, visible snapshot until both of the
preconditions listed above are met, at which point it is destroyed.
An inclusive range of snapshots may be specified by separating the first and last
snapshots with a percent sign. The first and/or last snapshots may be left blank, in
which case the filesystem's oldest or newest snapshot will be implied.
Multiple snapshots (or ranges of snapshots) of the same filesystem or volume may be
specified in a comma-separated list of snapshots. Only the snapshot's short name (the
part after the @) should be specified when using a range or comma-separated list to
identify multiple snapshots.
-R Recursively destroy all clones of these snapshots, including the clones, snapshots,
and children. If this flag is specified, the -d flag will have no effect.
-d Destroy immediately. If a snapshot cannot be destroyed now, mark it for deferred
destruction.
-n Do a dry-run ("No-op") deletion. No data will be deleted. This is useful in
conjunction with the -p or -v flags to determine what data would be deleted.
-p Print machine-parsable verbose information about the deleted data.
-r Destroy (or mark for deferred deletion) all snapshots with this name in descendent
file systems.
-v Print verbose information about the deleted data.
Extreme care should be taken when applying either the -r or the -R options, as they
can destroy large portions of a pool and cause unexpected behavior for mounted file
systems in use.
zfs destroy filesystem|volume#bookmark
The given bookmark is destroyed.
zfs snapshot [-r] [-o property=value]... filesystem@snapname|volume@snapname...
Creates snapshots with the given names. All previous modifications by successful system
calls to the file system are part of the snapshots. Snapshots are taken atomically, so
that all snapshots correspond to the same moment in time. zfs snap can be used as an
alias for zfs snapshot. See the Snapshots section for details.
-o property=value
Sets the specified property; see zfs create for details.
-r Recursively create snapshots of all descendent datasets
zfs rollback [-Rfr] snapshot
Roll back the given dataset to a previous snapshot. When a dataset is rolled back, all
data that has changed since the snapshot is discarded, and the dataset reverts to the
state at the time of the snapshot. By default, the command refuses to roll back to a
snapshot other than the most recent one. In order to do so, all intermediate snapshots
and bookmarks must be destroyed by specifying the -r option.
The -rR options do not recursively destroy the child snapshots of a recursive snapshot.
Only direct snapshots of the specified filesystem are destroyed by either of these
options. To completely roll back a recursive snapshot, you must rollback the individual
child snapshots.
-R Destroy any more recent snapshots and bookmarks, as well as any clones of those
snapshots.
-f Used with the -R option to force an unmount of any clone file systems that are to be
destroyed.
-r Destroy any snapshots and bookmarks more recent than the one specified.
zfs clone [-p] [-o property=value]... snapshot filesystem|volume
Creates a clone of the given snapshot. See the Clones section for details. The target
dataset can be located anywhere in the ZFS hierarchy, and is created as the same type as
the original.
-o property=value
Sets the specified property; see zfs create for details.
-p Creates all the non-existing parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent. If the target filesystem or volume already exists, the operation completes
successfully.
zfs promote clone-filesystem
Promotes a clone file system to no longer be dependent on its "origin" snapshot. This
makes it possible to destroy the file system that the clone was created from. The clone
parent-child dependency relationship is reversed, so that the origin file system becomes a
clone of the specified file system.
The snapshot that was cloned, and any snapshots previous to this snapshot, are now owned
by the promoted clone. The space they use moves from the origin file system to the
promoted clone, so enough space must be available to accommodate these snapshots. No new
space is consumed by this operation, but the space accounting is adjusted. The promoted
clone must not have any conflicting snapshot names of its own. The rename subcommand can
be used to rename any conflicting snapshots.
zfs rename [-f] filesystem|volume|snapshot filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
Renames the given dataset. The new target can be located anywhere in the ZFS hierarchy,
with the exception of snapshots. Snapshots can only be renamed within the parent file
system or volume. When renaming a snapshot, the parent file system of the snapshot does
not need to be specified as part of the second argument. Renamed file systems can inherit
new mount points, in which case they are unmounted and remounted at the new mount point.
-f Force unmount any filesystems that need to be unmounted in the process.
-p Creates all the nonexistent parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent.
zfs rename -r snapshot snapshot
Recursively rename the snapshots of all descendent datasets. Snapshots are the only
dataset that can be renamed recursively.
zfs list [-r|-d depth] [-Hp] [-o property[,property]...] [-s property]... [-S property]...
[-t type[,type]...] [filesystem|volume|snapshot]...
Lists the property information for the given datasets in tabular form. If specified, you
can list property information by the absolute pathname or the relative pathname. By
default, all file systems and volumes are displayed. Snapshots are displayed if the
listsnaps property is on (the default is off). The following fields are displayed: name,
used, available, referenced, mountpoint.
-H Used for scripting mode. Do not print headers and separate fields by a single tab
instead of arbitrary white space.
-S property
Same as the -s option, but sorts by property in descending order.
-d depth
Recursively display any children of the dataset, limiting the recursion to depth. A
depth of 1 will display only the dataset and its direct children.
-o property
A comma-separated list of properties to display. The property must be:
• One of the properties described in the Native Properties section
• A user property
• The value name to display the dataset name
• The value space to display space usage properties on file systems and volumes.
This is a shortcut for specifying -o
name,avail,used,usedsnap,usedds,usedrefreserv,usedchild -t filesystem,volume
syntax.
-p Display numbers in parsable (exact) values.
-r Recursively display any children of the dataset on the command line.
-s property
A property for sorting the output by column in ascending order based on the value of
the property. The property must be one of the properties described in the Properties
section or the value name to sort by the dataset name. Multiple properties can be
specified at one time using multiple -s property options. Multiple -s options are
evaluated from left to right in decreasing order of importance. The following is a
list of sorting criteria:
• Numeric types sort in numeric order.
• String types sort in alphabetical order.
• Types inappropriate for a row sort that row to the literal bottom, regardless of
the specified ordering.
If no sorting options are specified the existing behavior of zfs list is preserved.
-t type
A comma-separated list of types to display, where type is one of filesystem, snapshot,
volume, bookmark, or all. For example, specifying -t snapshot displays only
snapshots.
zfs set property=value [property=value]... filesystem|volume|snapshot...
Sets the property or list of properties to the given value(s) for each dataset. Only some
properties can be edited. See the Properties section for more information on what
properties can be set and acceptable values. Numeric values can be specified as exact
values, or in a human-readable form with a suffix of B, K, M, G, T, P, E, Z (for bytes,
kilobytes, megabytes, gigabytes, terabytes, petabytes, exabytes, or zettabytes,
respectively). User properties can be set on snapshots. For more information, see the
User Properties section.
zfs get [-r|-d depth] [-Hp] [-o field[,field]...] [-s source[,source]...] [-t
type[,type]...] all | property[,property]... [filesystem|volume|snapshot|bookmark]...
Displays properties for the given datasets. If no datasets are specified, then the
command displays properties for all datasets on the system. For each property, the
following columns are displayed:
name Dataset name
property Property name
value Property value
source Property source local, default, inherited,
temporary, received or none (-).
All columns are displayed by default, though this can be controlled by using the -o
option. This command takes a comma-separated list of properties as described in the
Native Properties and User Properties sections.
The value all can be used to display all properties that apply to the given dataset's type
(filesystem, volume, snapshot, or bookmark).
-H Display output in a form more easily parsed by scripts. Any headers are omitted, and
fields are explicitly separated by a single tab instead of an arbitrary amount of
space.
-d depth
Recursively display any children of the dataset, limiting the recursion to depth. A
depth of 1 will display only the dataset and its direct children.
-o field
A comma-separated list of columns to display. name,property,value,source is the
default value.
-p Display numbers in parsable (exact) values.
-r Recursively display properties for any children.
-s source
A comma-separated list of sources to display. Those properties coming from a source
other than those in this list are ignored. Each source must be one of the following:
local, default, inherited, temporary, received, and none. The default value is all
sources.
-t type
A comma-separated list of types to display, where type is one of filesystem, snapshot,
volume, bookmark, or all.
zfs inherit [-rS] property filesystem|volume|snapshot...
Clears the specified property, causing it to be inherited from an ancestor, restored to
default if no ancestor has the property set, or with the -S option reverted to the
received value if one exists. See the Properties section for a listing of default values,
and details on which properties can be inherited.
-r Recursively inherit the given property for all children.
-S Revert the property to the received value if one exists; otherwise operate as if the
-S option was not specified.
zfs upgrade
Displays a list of file systems that are not the most recent version.
zfs upgrade -v
Displays a list of currently supported file system versions.
zfs upgrade [-r] [-V version] -a | filesystem
Upgrades file systems to a new on-disk version. Once this is done, the file systems will
no longer be accessible on systems running older versions of the software. zfs send
streams generated from new snapshots of these file systems cannot be accessed on systems
running older versions of the software.
In general, the file system version is independent of the pool version. See zpool(8) for
information on the zpool upgrade command.
In some cases, the file system version and the pool version are interrelated and the pool
version must be upgraded before the file system version can be upgraded.
-V version
Upgrade to the specified version. If the -V flag is not specified, this command
upgrades to the most recent version. This option can only be used to increase the
version number, and only up to the most recent version supported by this software.
-a Upgrade all file systems on all imported pools.
filesystem
Upgrade the specified file system.
-r Upgrade the specified file system and all descendent file systems.
zfs userspace [-Hinp] [-o field[,field]...] [-s field]... [-S field]... [-t type[,type]...]
filesystem|snapshot
Displays space consumed by, and quotas on, each user in the specified filesystem or
snapshot. This corresponds to the userused@user, userobjused@user, userquota@user, and
userobjquota@user properties.
-H Do not print headers, use tab-delimited output.
-S field
Sort by this field in reverse order. See -s.
-i Translate SID to POSIX ID. The POSIX ID may be ephemeral if no mapping exists.
Normal POSIX interfaces (for example, stat(2), ls -l) perform this translation, so the
-i option allows the output from zfs userspace to be compared directly with those
utilities. However, -i may lead to confusion if some files were created by an SMB
user before a SMB-to-POSIX name mapping was established. In such a case, some files
will be owned by the SMB entity and some by the POSIX entity. However, the -i option
will report that the POSIX entity has the total usage and quota for both.
-n Print numeric ID instead of user/group name.
-o field[,field]...
Display only the specified fields from the following set: type, name, used, quota.
The default is to display all fields.
-p Use exact (parsable) numeric output.
-s field
Sort output by this field. The -s and -S flags may be specified multiple times to
sort first by one field, then by another. The default is -s type -s name.
-t type[,type]...
Print only the specified types from the following set: all, posixuser, smbuser,
posixgroup, smbgroup. The default is -t posixuser,smbuser. The default can be
changed to include group types.
zfs groupspace [-Hinp] [-o field[,field]...] [-s field]... [-S field]... [-t type[,type]...]
filesystem|snapshot
Displays space consumed by, and quotas on, each group in the specified filesystem or
snapshot. This subcommand is identical to zfs userspace, except that the default types to
display are -t posixgroup,smbgroup.
zfs projectspace [-Hp] [-o field[,field]...] [-s field]... [-S field]... filesystem|snapshot
Displays space consumed by, and quotas on, each project in the specified filesystem or
snapshot. This subcommand is identical to zfs userspace, except that the project
identifier is numeral, not name. So need neither the option -i for SID to POSIX ID nor -n
for numeric ID, nor -t for types.
zfs project [-d|-r] file|directory...
List project identifier (ID) and inherit flag of file(s) or directories.
-d Show the directory project ID and inherit flag, not its childrens. It will overwrite
the former specified -r option.
-r Show on subdirectories recursively. It will overwrite the former specified -d option.
zfs project -C [-kr] file|directory...
Clear project inherit flag and/or ID on the file(s) or directories.
-k Keep the project ID unchanged. If not specified, the project ID will be reset as zero.
-r Clear on subdirectories recursively.
zfs project -c [-0] [-d|-r] [-p id] file|directory...
Check project ID and inherit flag on the file(s) or directories, report the entries
without project inherit flag or with different project IDs from the specified (via -p
option) value or the target directory's project ID.
-0 Print file name with a trailing NUL instead of newline (by default), like "find
-print0".
-d Check the directory project ID and inherit flag, not its childrens. It will overwrite
the former specified -r option.
-p Specify the referenced ID for comparing with the target file(s) or directories'
project IDs. If not specified, the target (top) directory's project ID will be used as
the referenced one.
-r Check on subdirectories recursively. It will overwrite the former specified -d option.
zfs project [-p id] [-rs] file|directory...
Set project ID and/or inherit flag on the file(s) or directories.
-p Set the file(s)' or directories' project ID with the given value.
-r Set on subdirectories recursively.
-s Set project inherit flag on the given file(s) or directories. It is usually used for
setup tree quota on the directory target with -r option specified together. When setup
tree quota, by default the directory's project ID will be set to all its descendants
unless you specify the project ID via -p option explicitly.
zfs mount
Displays all ZFS file systems currently mounted.
zfs mount [-Olv] [-o options] -a | filesystem
Mount ZFS filesystem on a path described by its mountpoint property, if the path exists
and is empty. If mountpoint is set to legacy, the filesystem should be instead mounted
using mount(8).
-O Perform an overlay mount. Allows mounting in non-empty mountpoint. See mount(8) for
more information.
-a Mount all available ZFS file systems. Invoked automatically as part of the boot
process if configured.
filesystem
Mount the specified filesystem.
-o options
An optional, comma-separated list of mount options to use temporarily for the duration
of the mount. See the Temporary Mount Point Properties section for details.
-l Load keys for encrypted filesystems as they are being mounted. This is equivalent to
executing zfs load-key on each encryption root before mounting it. Note that if a
filesystem has a keylocation of prompt this will cause the terminal to interactively
block after asking for the key.
-v Report mount progress.
zfs unmount [-f] -a | filesystem|mountpoint
Unmounts currently mounted ZFS file systems.
-a Unmount all available ZFS file systems. Invoked automatically as part of the shutdown
process.
filesystem|mountpoint
Unmount the specified filesystem. The command can also be given a path to a ZFS file
system mount point on the system.
-f Forcefully unmount the file system, even if it is currently in use.
zfs share -a | filesystem
Shares available ZFS file systems.
-a Share all available ZFS file systems. Invoked automatically as part of the boot
process.
filesystem
Share the specified filesystem according to the sharenfs and sharesmb properties.
File systems are shared when the sharenfs or sharesmb property is set.
zfs unshare -a | filesystem|mountpoint
Unshares currently shared ZFS file systems.
-a Unshare all available ZFS file systems. Invoked automatically as part of the shutdown
process.
filesystem|mountpoint
Unshare the specified filesystem. The command can also be given a path to a ZFS file
system shared on the system.
zfs bookmark snapshot bookmark
Creates a bookmark of the given snapshot. Bookmarks mark the point in time when the
snapshot was created, and can be used as the incremental source for a zfs send command.
This feature must be enabled to be used. See zpool-features(5) for details on ZFS feature
flags and the bookmarks feature.
zfs send [-DLPRbcehnpvw] [[-I|-i] snapshot] snapshot
Creates a stream representation of the second snapshot, which is written to standard
output. The output can be redirected to a file or to a different system (for example,
using ssh(1)). By default, a full stream is generated.
-D, --dedup
Generate a deduplicated stream. Blocks which would have been sent multiple times in
the send stream will only be sent once. The receiving system must also support this
feature to receive a deduplicated stream. This flag can be used regardless of the
dataset's dedup property, but performance will be much better if the filesystem uses a
dedup-capable checksum (for example, sha256).
-I snapshot
Generate a stream package that sends all intermediary snapshots from the first
snapshot to the second snapshot. For example, -I @a fs@d is similar to -i @a fs@b; -i
@b fs@c; -i @c fs@d. The incremental source may be specified as with the -i option.
-L, --large-block
Generate a stream which may contain blocks larger than 128KB. This flag has no effect
if the large_blocks pool feature is disabled, or if the recordsize property of this
filesystem has never been set above 128KB. The receiving system must have the
large_blocks pool feature enabled as well. See zpool-features(5) for details on ZFS
feature flags and the large_blocks feature.
-P, --parsable
Print machine-parsable verbose information about the stream package generated.
-R, --replicate
Generate a replication stream package, which will replicate the specified file system,
and all descendent file systems, up to the named snapshot. When received, all
properties, snapshots, descendent file systems, and clones are preserved.
If the -i or -I flags are used in conjunction with the -R flag, an incremental
replication stream is generated. The current values of properties, and current
snapshot and file system names are set when the stream is received. If the -F flag is
specified when this stream is received, snapshots and file systems that do not exist
on the sending side are destroyed. If the -R flag is used to send encrypted datasets,
then -w must also be specified.
-e, --embed
Generate a more compact stream by using WRITE_EMBEDDED records for blocks which are
stored more compactly on disk by the embedded_data pool feature. This flag has no
effect if the embedded_data feature is disabled. The receiving system must have the
embedded_data feature enabled. If the lz4_compress feature is active on the sending
system, then the receiving system must have that feature enabled as well. Datasets
that are sent with this flag may not be received as an encrypted dataset, since
encrypted datasets cannot use the embedded_data feature. See zpool-features(5) for
details on ZFS feature flags and the embedded_data feature.
-b, --backup
Sends only received property values whether or not they are overridden by local
settings, but only if the dataset has ever been received. Use this option when you
want zfs receive to restore received properties backed up on the sent dataset and to
avoid sending local settings that may have nothing to do with the source dataset, but
only with how the data is backed up.
-c, --compressed
Generate a more compact stream by using compressed WRITE records for blocks which are
compressed on disk and in memory (see the compression property for details). If the
lz4_compress feature is active on the sending system, then the receiving system must
have that feature enabled as well. If the large_blocks feature is enabled on the
sending system but the -L option is not supplied in conjunction with -c, then the data
will be decompressed before sending so it can be split into smaller block sizes.
-w, --raw
For encrypted datasets, send data exactly as it exists on disk. This allows backups to
be taken even if encryption keys are not currently loaded. The backup may then be
received on an untrusted machine since that machine will not have the encryption keys
to read the protected data or alter it without being detected. Upon being received,
the dataset will have the same encryption keys as it did on the send side, although
the keylocation property will be defaulted to prompt if not otherwise provided. For
unencrypted datasets, this flag will be equivalent to -Lec. Note that if you do not
use this flag for sending encrypted datasets, data will be sent unencrypted and may be
re-encrypted with a different encryption key on the receiving system, which will
disable the ability to do a raw send to that system for incrementals.
-h, --holds
Generate a stream package that includes any snapshot holds (created with the zfs hold
command), and indicating to zfs receive that the holds be applied to the dataset on
the receiving system.
-i snapshot
Generate an incremental stream from the first snapshot (the incremental source) to the
second snapshot (the incremental target). The incremental source can be specified as
the last component of the snapshot name (the @ character and following) and it is
assumed to be from the same file system as the incremental target.
If the destination is a clone, the source may be the origin snapshot, which must be
fully specified (for example, pool/fs@origin, not just @origin).
-n, --dryrun
Do a dry-run ("No-op") send. Do not generate any actual send data. This is useful in
conjunction with the -v or -P flags to determine what data will be sent. In this
case, the verbose output will be written to standard output (contrast with a
non-dry-run, where the stream is written to standard output and the verbose output
goes to standard error).
-p, --props
Include the dataset's properties in the stream. This flag is implicit when -R is
specified. The receiving system must also support this feature. Sends of encrypted
datasets must use -w when using this flag.
-v, --verbose
Print verbose information about the stream package generated. This information
includes a per-second report of how much data has been sent.
The format of the stream is committed. You will be able to receive your streams on
future versions of ZFS.
zfs send [-LPcenvw] [-i snapshot|bookmark] filesystem|volume|snapshot
Generate a send stream, which may be of a filesystem, and may be incremental from a
bookmark. If the destination is a filesystem or volume, the pool must be read-only, or
the filesystem must not be mounted. When the stream generated from a filesystem or volume
is received, the default snapshot name will be "--head--".
-L, --large-block
Generate a stream which may contain blocks larger than 128KB. This flag has no effect
if the large_blocks pool feature is disabled, or if the recordsize property of this
filesystem has never been set above 128KB. The receiving system must have the
large_blocks pool feature enabled as well. See zpool-features(5) for details on ZFS
feature flags and the large_blocks feature.
-P, --parsable
Print machine-parsable verbose information about the stream package generated.
-c, --compressed
Generate a more compact stream by using compressed WRITE records for blocks which are
compressed on disk and in memory (see the compression property for details). If the
lz4_compress feature is active on the sending system, then the receiving system must
have that feature enabled as well. If the large_blocks feature is enabled on the
sending system but the -L option is not supplied in conjunction with -c, then the data
will be decompressed before sending so it can be split into smaller block sizes.
-w, --raw
For encrypted datasets, send data exactly as it exists on disk. This allows backups to
be taken even if encryption keys are not currently loaded. The backup may then be
received on an untrusted machine since that machine will not have the encryption keys
to read the protected data or alter it without being detected. Upon being received,
the dataset will have the same encryption keys as it did on the send side, although
the keylocation property will be defaulted to prompt if not otherwise provided. For
unencrypted datasets, this flag will be equivalent to -Lec. Note that if you do not
use this flag for sending encrypted datasets, data will be sent unencrypted and may be
re-encrypted with a different encryption key on the receiving system, which will
disable the ability to do a raw send to that system for incrementals.
-e, --embed
Generate a more compact stream by using WRITE_EMBEDDED records for blocks which are
stored more compactly on disk by the embedded_data pool feature. This flag has no
effect if the embedded_data feature is disabled. The receiving system must have the
embedded_data feature enabled. If the lz4_compress feature is active on the sending
system, then the receiving system must have that feature enabled as well. Datasets
that are sent with this flag may not be received as an encrypted dataset, since
encrypted datasets cannot use the embedded_data feature. See zpool-features(5) for
details on ZFS feature flags and the embedded_data feature.
-i snapshot|bookmark
Generate an incremental send stream. The incremental source must be an earlier
snapshot in the destination's history. It will commonly be an earlier snapshot in the
destination's file system, in which case it can be specified as the last component of
the name (the # or @ character and following).
If the incremental target is a clone, the incremental source can be the origin
snapshot, or an earlier snapshot in the origin's filesystem, or the origin's origin,
etc.
-n, --dryrun
Do a dry-run ("No-op") send. Do not generate any actual send data. This is useful in
conjunction with the -v or -P flags to determine what data will be sent. In this
case, the verbose output will be written to standard output (contrast with a
non-dry-run, where the stream is written to standard output and the verbose output
goes to standard error).
-v, --verbose
Print verbose information about the stream package generated. This information
includes a per-second report of how much data has been sent.
zfs send [-Penv] -t receive_resume_token
Creates a send stream which resumes an interrupted receive. The receive_resume_token is
the value of this property on the filesystem or volume that was being received into. See
the documentation for zfs receive -s for more details.
zfs receive [-Fhnsuv] [-o origin=snapshot] [-o property=value] [-x property]
filesystem|volume|snapshot
zfs receive [-Fhnsuv] [-d|-e] [-o origin=snapshot] [-o property=value] [-x property]
filesystem
Creates a snapshot whose contents are as specified in the stream provided on standard
input. If a full stream is received, then a new file system is created as well. Streams
are created using the zfs send subcommand, which by default creates a full stream. zfs
recv can be used as an alias for zfs receive.
If an incremental stream is received, then the destination file system must already exist,
and its most recent snapshot must match the incremental stream's source. For zvols, the
destination device link is destroyed and recreated, which means the zvol cannot be
accessed during the receive operation.
When a snapshot replication package stream that is generated by using the zfs send -R
command is received, any snapshots that do not exist on the sending location are destroyed
by using the zfs destroy -d command.
If -o property=value or -x property is specified, it applies to the effective value of the
property throughout the entire subtree of replicated datasets. Effective property values
will be set ( -o ) or inherited ( -x ) on the topmost in the replicated subtree. In
descendant datasets, if the property is set by the send stream, it will be overridden by
forcing the property to be inherited from the top‐most file system. Received properties
are retained in spite of being overridden and may be restored with zfs inherit -S.
Specifying -o origin=snapshot is a special case because, even if origin is a read-only
property and cannot be set, it's allowed to receive the send stream as a clone of the
given snapshot.
Raw encrypted send streams (created with zfs send -w ) may only be received as is, and
cannot be re-encrypted, decrypted, or recompressed by the receive process. Unencrypted
streams can be received as encrypted datasets, either through inheritance or by specifying
encryption parameters with the -o options. Note that the keylocation property cannot be
overridden to prompt during a receive. This is because the receive process itself is
already using stdin for the send stream. Instead, the property can be overridden after the
receive completes.
The added security provided by raw sends adds some restrictions to the send and receive
process. ZFS will not allow a mix of raw receives and non-raw receives. Specifically, any
raw incremental receives that are attempted after a non-raw receive will fail. Non-raw
receives do not have this restriction and, therefore, are always possible. Because of
this, it is best practice to always use either raw sends for their security benefits or
non-raw sends for their flexibility when working with encrypted datasets, but not a
combination.
The reason for this restriction stems from the inherent restrictions of the AEAD ciphers
that ZFS uses to encrypt data. When using ZFS native encryption, each block of data is
encrypted against a randomly generated number known as the "initialization vector" (IV),
which is stored in the filesystem metadata. This number is required by the encryption
algorithms whenever the data is to be decrypted. Together, all of the IVs provided for all
of the blocks in a given snapshot are collectively called an "IV set". When ZFS performs a
raw send, the IV set is transferred from the source to the destination in the send stream.
When ZFS performs a non-raw send, the data is decrypted by the source system and re-
encrypted by the destination system, creating a snapshot with effectively the same data,
but a different IV set. In order for decryption to work after a raw send, ZFS must ensure
that the IV set used on both the source and destination side match. When an incremental
raw receive is performed on top of an existing snapshot, ZFS will check to confirm that
the "from" snapshot on both the source and destination were using the same IV set,
ensuring the new IV set is consistent.
The name of the snapshot (and file system, if a full stream is received) that this
subcommand creates depends on the argument type and the use of the -d or -e options.
If the argument is a snapshot name, the specified snapshot is created. If the argument is
a file system or volume name, a snapshot with the same name as the sent snapshot is
created within the specified filesystem or volume. If neither of the -d or -e options are
specified, the provided target snapshot name is used exactly as provided.
The -d and -e options cause the file system name of the target snapshot to be determined
by appending a portion of the sent snapshot's name to the specified target filesystem. If
the -d option is specified, all but the first element of the sent snapshot's file system
path (usually the pool name) is used and any required intermediate file systems within the
specified one are created. If the -e option is specified, then only the last element of
the sent snapshot's file system name (i.e. the name of the source file system itself) is
used as the target file system name.
-F Force a rollback of the file system to the most recent snapshot before performing the
receive operation. If receiving an incremental replication stream (for example, one
generated by zfs send -R [-i|-I]), destroy snapshots and file systems that do not
exist on the sending side.
-d Discard the first element of the sent snapshot's file system name, using the remaining
elements to determine the name of the target file system for the new snapshot as
described in the paragraph above.
-e Discard all but the last element of the sent snapshot's file system name, using that
element to determine the name of the target file system for the new snapshot as
described in the paragraph above.
-h Skip the receive of holds. There is no effect if holds are not sent.
-n Do not actually receive the stream. This can be useful in conjunction with the -v
option to verify the name the receive operation would use.
-o origin=snapshot
Forces the stream to be received as a clone of the given snapshot. If the stream is a
full send stream, this will create the filesystem described by the stream as a clone
of the specified snapshot. Which snapshot was specified will not affect the success
or failure of the receive, as long as the snapshot does exist. If the stream is an
incremental send stream, all the normal verification will be performed.
-o property=value
Sets the specified property as if the command zfs set property=value was invoked
immediately before the receive. When receiving a stream from zfs send -R, causes the
property to be inherited by all descendant datasets, as through zfs inherit property
was run on any descendant datasets that have this property set on the sending system.
Any editable property can be set at receive time. Set-once properties bound to the
received data, such as normalization and casesensitivity, cannot be set at receive
time even when the datasets are newly created by zfs receive. Additionally both
settable properties version and volsize cannot be set at receive time.
The -o option may be specified multiple times, for different properties. An error
results if the same property is specified in multiple -o or -x options.
The -o option may also be used to override encryption properties upon initial receive.
This allows unencrypted streams to be received as encrypted datasets. To cause the
received dataset (or root dataset of a recursive stream) to be received as an
encryption root, specify encryption properties in the same manner as is required for
zfs create. For instance:
# zfs send tank/test@snap1 | zfs recv -o encryption=on -o keyformat=passphrase -o keylocation=file:///path/to/keyfile
Note that [-o keylocation=prompt] may not be specified here, since stdin is already
being utilized for the send stream. Once the receive has completed, you can use zfs
set to change this setting after the fact. Similarly, you can receive a dataset as an
encrypted child by specifying [-x encryption] to force the property to be inherited.
Overriding encryption properties (except for keylocation) is not possible with raw
send streams.
-s If the receive is interrupted, save the partially received state, rather than deleting
it. Interruption may be due to premature termination of the stream (e.g. due to
network failure or failure of the remote system if the stream is being read over a
network connection), a checksum error in the stream, termination of the zfs receive
process, or unclean shutdown of the system.
The receive can be resumed with a stream generated by zfs send -t token, where the
token is the value of the receive_resume_token property of the filesystem or volume
which is received into.
To use this flag, the storage pool must have the extensible_dataset feature enabled.
See zpool-features(5) for details on ZFS feature flags.
-u File system that is associated with the received stream is not mounted.
-v Print verbose information about the stream and the time required to perform the
receive operation.
-x property
Ensures that the effective value of the specified property after the receive is
unaffected by the value of that property in the send stream (if any), as if the
property had been excluded from the send stream.
If the specified property is not present in the send stream, this option does nothing.
If a received property needs to be overridden, the effective value will be set or
inherited, depending on whether the property is inheritable or not.
In the case of an incremental update, -x leaves any existing local setting or explicit
inheritance unchanged.
All -o restrictions (e.g. set-once) apply equally to -x.
zfs receive -A filesystem|volume
Abort an interrupted zfs receive -s, deleting its saved partially received state.
zfs allow filesystem|volume
Displays permissions that have been delegated on the specified filesystem or volume. See
the other forms of zfs allow for more information.
Delegations are supported under Linux with the exception of mount, unmount, mountpoint,
canmount, rename, and share. These permissions cannot be delegated because the Linux
mount(8) command restricts modifications of the global namespace to the root user.
zfs allow [-dglu] user|group[,user|group]... perm|@setname[,perm|@setname]...
filesystem|volume
zfs allow [-dl] -e|everyone perm|@setname[,perm|@setname]... filesystem|volume
Delegates ZFS administration permission for the file systems to non-privileged users.
-d Allow only for the descendent file systems.
-e|everyone
Specifies that the permissions be delegated to everyone.
-g group[,group]...
Explicitly specify that permissions are delegated to the group.
-l Allow "locally" only for the specified file system.
-u user[,user]...
Explicitly specify that permissions are delegated to the user.
user|group[,user|group]...
Specifies to whom the permissions are delegated. Multiple entities can be specified
as a comma-separated list. If neither of the -gu options are specified, then the
argument is interpreted preferentially as the keyword everyone, then as a user name,
and lastly as a group name. To specify a user or group named "everyone", use the -g
or -u options. To specify a group with the same name as a user, use the -g options.
perm|@setname[,perm|@setname]...
The permissions to delegate. Multiple permissions may be specified as a comma-
separated list. Permission names are the same as ZFS subcommand and property names.
See the property list below. Property set names, which begin with @, may be
specified. See the -s form below for details.
If neither of the -dl options are specified, or both are, then the permissions are allowed
for the file system or volume, and all of its descendents.
Permissions are generally the ability to use a ZFS subcommand or change a ZFS property.
The following permissions are available:
NAME TYPE NOTES
allow subcommand Must also have the permission that is
being allowed
clone subcommand Must also have the 'create' ability and
'mount' ability in the origin file system
create subcommand Must also have the 'mount' ability.
Must also have the 'refreservation' ability to
create a non-sparse volume.
destroy subcommand Must also have the 'mount' ability
diff subcommand Allows lookup of paths within a dataset
given an object number, and the ability
to create snapshots necessary to
'zfs diff'.
load-key subcommand Allows loading and unloading of encryption key
(see 'zfs load-key' and 'zfs unload-key').
change-key subcommand Allows changing an encryption key via
'zfs change-key'.
mount subcommand Allows mount/umount of ZFS datasets
promote subcommand Must also have the 'mount' and 'promote'
ability in the origin file system
receive subcommand Must also have the 'mount' and 'create'
ability
rename subcommand Must also have the 'mount' and 'create'
ability in the new parent
rollback subcommand Must also have the 'mount' ability
send subcommand
share subcommand Allows sharing file systems over NFS
or SMB protocols
snapshot subcommand Must also have the 'mount' ability
groupquota other Allows accessing any groupquota@...
property
groupused other Allows reading any groupused@... property
userprop other Allows changing any user property
userquota other Allows accessing any userquota@...
property
userused other Allows reading any userused@... property
projectobjquota other Allows accessing any projectobjquota@...
property
projectquota other Allows accessing any projectquota@... property
projectobjused other Allows reading any projectobjused@... property
projectused other Allows reading any projectused@... property
aclinherit property
acltype property
atime property
canmount property
casesensitivity property
checksum property
compression property
copies property
devices property
exec property
filesystem_limit property
mountpoint property
nbmand property
normalization property
primarycache property
quota property
readonly property
recordsize property
refquota property
refreservation property
reservation property
secondarycache property
setuid property
sharenfs property
sharesmb property
snapdir property
snapshot_limit property
utf8only property
version property
volblocksize property
volsize property
vscan property
xattr property
zoned property
zfs allow -c perm|@setname[,perm|@setname]... filesystem|volume
Sets "create time" permissions. These permissions are granted (locally) to the creator of
any newly-created descendent file system.
zfs allow -s @setname perm|@setname[,perm|@setname]... filesystem|volume
Defines or adds permissions to a permission set. The set can be used by other zfs allow
commands for the specified file system and its descendents. Sets are evaluated
dynamically, so changes to a set are immediately reflected. Permission sets follow the
same naming restrictions as ZFS file systems, but the name must begin with @, and can be
no more than 64 characters long.
zfs unallow [-dglru] user|group[,user|group]... [perm|@setname[,perm|@setname]...]
filesystem|volume
zfs unallow [-dlr] -e|everyone [perm|@setname[,perm|@setname]...] filesystem|volume
zfs unallow [-r] -c [perm|@setname[,perm|@setname]...] filesystem|volume
Removes permissions that were granted with the zfs allow command. No permissions are
explicitly denied, so other permissions granted are still in effect. For example, if the
permission is granted by an ancestor. If no permissions are specified, then all
permissions for the specified user, group, or everyone are removed. Specifying everyone
(or using the -e option) only removes the permissions that were granted to everyone, not
all permissions for every user and group. See the zfs allow command for a description of
the -ldugec options.
-r Recursively remove the permissions from this file system and all descendents.
zfs unallow [-r] -s @setname [perm|@setname[,perm|@setname]...] filesystem|volume
Removes permissions from a permission set. If no permissions are specified, then all
permissions are removed, thus removing the set entirely.
zfs hold [-r] tag snapshot...
Adds a single reference, named with the tag argument, to the specified snapshot or
snapshots. Each snapshot has its own tag namespace, and tags must be unique within that
space.
If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs destroy
command return EBUSY.
-r Specifies that a hold with the given tag is applied recursively to the snapshots of
all descendent file systems.
zfs holds [-rH] snapshot...
Lists all existing user references for the given snapshot or snapshots.
-r Lists the holds that are set on the named descendent snapshots, in addition to listing
the holds on the named snapshot.
-H Do not print headers, use tab-delimited output.
zfs release [-r] tag snapshot...
Removes a single reference, named with the tag argument, from the specified snapshot or
snapshots. The tag must already exist for each snapshot. If a hold exists on a snapshot,
attempts to destroy that snapshot by using the zfs destroy command return EBUSY.
-r Recursively releases a hold with the given tag on the snapshots of all descendent file
systems.
zfs diff [-FHt] snapshot snapshot|filesystem
Display the difference between a snapshot of a given filesystem and another snapshot of
that filesystem from a later time or the current contents of the filesystem. The first
column is a character indicating the type of change, the other columns indicate pathname,
new pathname (in case of rename), change in link count, and optionally file type and/or
change time. The types of change are:
- The path has been removed
+ The path has been created
M The path has been modified
R The path has been renamed
-F Display an indication of the type of file, in a manner similar to the - option of
ls(1).
B Block device
C Character device
/ Directory
> Door
| Named pipe
@ Symbolic link
P Event port
= Socket
F Regular file
-H Give more parsable tab-separated output, without header lines and without arrows.
-t Display the path's inode change time as the first column of output.
zfs program [-jn] [-t instruction-limit] [-m memory-limit] pool script [--] arg1 ...
Executes script as a ZFS channel program on pool. The ZFS channel program interface
allows ZFS administrative operations to be run programmatically via a Lua script. The
entire script is executed atomically, with no other administrative operations taking
effect concurrently. A library of ZFS calls is made available to channel program scripts.
Channel programs may only be run with root privileges.
For full documentation of the ZFS channel program interface, see the manual page for
zfs-program(8).
-j
Display channel program output in JSON format. When this flag is specified and standard
output is empty - channel program encountered an error. The details of such an error
will be printed to standard error in plain text.
-n
Executes a read-only channel program, which runs faster. The program cannot change on-
disk state by calling functions from the zfs.sync submodule. The program can be used to
gather information such as properties and determining if changes would succeed
(zfs.check.*). Without this flag, all pending changes must be synced to disk before a
channel program can complete.
-t instruction-limit
Limit the number of Lua instructions to execute. If a channel program executes more
than the specified number of instructions, it will be stopped and an error will be
returned. The default limit is 10 million instructions, and it can be set to a maximum
of 100 million instructions.
-m memory-limit
Memory limit, in bytes. If a channel program attempts to allocate more memory than the
given limit, it will be stopped and an error returned. The default memory limit is 10
MB, and can be set to a maximum of 100 MB.
All remaining argument strings are passed directly to the channel program as arguments.
See zfs-program(8) for more information.
zfs load-key [-nr] [-L keylocation] -a | filesystem
Load the key for filesystem, allowing it and all children that inherit the keylocation
property to be accessed. The key will be expected in the format specified by the keyformat
and location specified by the keylocation property. Note that if the keylocation is set to
prompt the terminal will interactively wait for the key to be entered. Loading a key will
not automatically mount the dataset. If that functionality is desired, zfs mount -l will
ask for the key and mount the dataset. Once the key is loaded the keystatus property will
become available.
-r Recursively loads the keys for the specified filesystem and all descendent encryption
roots.
-a Loads the keys for all encryption roots in all imported pools.
-n Do a dry-run ("No-op") load-key. This will cause zfs to simply check that the provided
key is correct. This command may be run even if the key is already loaded.
-L keylocation
Use keylocation instead of the keylocation property. This will not change the value of
the property on the dataset. Note that if used with either -r or -a, keylocation may
only be given as prompt.
zfs unload-key [-r] -a | filesystem
Unloads a key from ZFS, removing the ability to access the dataset and all of its children
that inherit the keylocation property. This requires that the dataset is not currently
open or mounted. Once the key is unloaded the keystatus property will become unavailable.
-r Recursively unloads the keys for the specified filesystem and all descendent
encryption roots.
-a Unloads the keys for all encryption roots in all imported pools.
zfs change-key [-l] [-o keylocation=value] [-o keyformat=value] [-o pbkdf2iters=value]
filesystem
zfs change-key -i [-l] filesystem
Allows a user to change the encryption key used to access a dataset. This command requires
that the existing key for the dataset is already loaded into ZFS. This command may also be
used to change the keylocation, keyformat, and pbkdf2iters properties as needed. If the
dataset was not previously an encryption root it will become one. Alternatively, the -i
flag may be provided to cause an encryption root to inherit the parent's key instead.
-l Ensures the key is loaded before attempting to change the key. This is effectively
equivalent to "zfs load-key filesystem; zfs change-key filesystem"
-o property=value
Allows the user to set encryption key properties ( keyformat, keylocation, and
pbkdf2iters ) while changing the key. This is the only way to alter keyformat and
pbkdf2iters after the dataset has been created.
-i Indicates that zfs should make filesystem inherit the key of its parent. Note that
this command can only be run on an encryption root that has an encrypted parent.
zfs version
Displays the software version of the zfs userland utility and the zfs kernel module.
EXIT STATUS
The zfs utility exits 0 on success, 1 if an error occurs, and 2 if invalid command line
options were specified.
EXAMPLES
Example 1 Creating a ZFS File System Hierarchy
The following commands create a file system named pool/home and a file system named
pool/home/bob. The mount point /export/home is set for the parent file system, and is
automatically inherited by the child file system.
# zfs create pool/home
# zfs set mountpoint=/export/home pool/home
# zfs create pool/home/bob
Example 2 Creating a ZFS Snapshot
The following command creates a snapshot named yesterday. This snapshot is mounted on
demand in the .zfs/snapshot directory at the root of the pool/home/bob file system.
# zfs snapshot pool/home/bob@yesterday
Example 3 Creating and Destroying Multiple Snapshots
The following command creates snapshots named yesterday of pool/home and all of its
descendent file systems. Each snapshot is mounted on demand in the .zfs/snapshot
directory at the root of its file system. The second command destroys the newly created
snapshots.
# zfs snapshot -r pool/home@yesterday
# zfs destroy -r pool/home@yesterday
Example 4 Disabling and Enabling File System Compression
The following command disables the compression property for all file systems under
pool/home. The next command explicitly enables compression for pool/home/anne.
# zfs set compression=off pool/home
# zfs set compression=on pool/home/anne
Example 5 Listing ZFS Datasets
The following command lists all active file systems and volumes in the system. Snapshots
are displayed if the listsnaps property is on. The default is off. See zpool(8) for more
information on pool properties.
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
pool 450K 457G 18K /pool
pool/home 315K 457G 21K /export/home
pool/home/anne 18K 457G 18K /export/home/anne
pool/home/bob 276K 457G 276K /export/home/bob
Example 6 Setting a Quota on a ZFS File System
The following command sets a quota of 50 Gbytes for pool/home/bob.
# zfs set quota=50G pool/home/bob
Example 7 Listing ZFS Properties
The following command lists all properties for pool/home/bob.
# zfs get all pool/home/bob
NAME PROPERTY VALUE SOURCE
pool/home/bob type filesystem -
pool/home/bob creation Tue Jul 21 15:53 2009 -
pool/home/bob used 21K -
pool/home/bob available 20.0G -
pool/home/bob referenced 21K -
pool/home/bob compressratio 1.00x -
pool/home/bob mounted yes -
pool/home/bob quota 20G local
pool/home/bob reservation none default
pool/home/bob recordsize 128K default
pool/home/bob mountpoint /pool/home/bob default
pool/home/bob sharenfs off default
pool/home/bob checksum on default
pool/home/bob compression on local
pool/home/bob atime on default
pool/home/bob devices on default
pool/home/bob exec on default
pool/home/bob setuid on default
pool/home/bob readonly off default
pool/home/bob zoned off default
pool/home/bob snapdir hidden default
pool/home/bob acltype off default
pool/home/bob aclinherit restricted default
pool/home/bob canmount on default
pool/home/bob xattr on default
pool/home/bob copies 1 default
pool/home/bob version 4 -
pool/home/bob utf8only off -
pool/home/bob normalization none -
pool/home/bob casesensitivity sensitive -
pool/home/bob vscan off default
pool/home/bob nbmand off default
pool/home/bob sharesmb off default
pool/home/bob refquota none default
pool/home/bob refreservation none default
pool/home/bob primarycache all default
pool/home/bob secondarycache all default
pool/home/bob usedbysnapshots 0 -
pool/home/bob usedbydataset 21K -
pool/home/bob usedbychildren 0 -
pool/home/bob usedbyrefreservation 0 -
The following command gets a single property value.
# zfs get -H -o value compression pool/home/bob
on
The following command lists all properties with local settings for pool/home/bob.
# zfs get -r -s local -o name,property,value all pool/home/bob
NAME PROPERTY VALUE
pool/home/bob quota 20G
pool/home/bob compression on
Example 8 Rolling Back a ZFS File System
The following command reverts the contents of pool/home/anne to the snapshot named
yesterday, deleting all intermediate snapshots.
# zfs rollback -r pool/home/anne@yesterday
Example 9 Creating a ZFS Clone
The following command creates a writable file system whose initial contents are the same
as pool/home/bob@yesterday.
# zfs clone pool/home/bob@yesterday pool/clone
Example 10 Promoting a ZFS Clone
The following commands illustrate how to test out changes to a file system, and then
replace the original file system with the changed one, using clones, clone promotion, and
renaming:
# zfs create pool/project/production
populate /pool/project/production with data
# zfs snapshot pool/project/production@today
# zfs clone pool/project/production@today pool/project/beta
make changes to /pool/project/beta and test them
# zfs promote pool/project/beta
# zfs rename pool/project/production pool/project/legacy
# zfs rename pool/project/beta pool/project/production
once the legacy version is no longer needed, it can be destroyed
# zfs destroy pool/project/legacy
Example 11 Inheriting ZFS Properties
The following command causes pool/home/bob and pool/home/anne to inherit the checksum
property from their parent.
# zfs inherit checksum pool/home/bob pool/home/anne
Example 12 Remotely Replicating ZFS Data
The following commands send a full stream and then an incremental stream to a remote
machine, restoring them into poolB/received/fs@a and poolB/received/fs@b, respectively.
poolB must contain the file system poolB/received, and must not initially contain
poolB/received/fs.
# zfs send pool/fs@a | \
ssh host zfs receive poolB/received/fs@a
# zfs send -i a pool/fs@b | \
ssh host zfs receive poolB/received/fs
Example 13 Using the zfs receive -d Option
The following command sends a full stream of poolA/fsA/fsB@snap to a remote machine,
receiving it into poolB/received/fsA/fsB@snap. The fsA/fsB@snap portion of the received
snapshot's name is determined from the name of the sent snapshot. poolB must contain the
file system poolB/received. If poolB/received/fsA does not exist, it is created as an
empty file system.
# zfs send poolA/fsA/fsB@snap | \
ssh host zfs receive -d poolB/received
Example 14 Setting User Properties
The following example sets the user-defined com.example:department property for a dataset.
# zfs set com.example:department=12345 tank/accounting
Example 15 Performing a Rolling Snapshot
The following example shows how to maintain a history of snapshots with a consistent
naming scheme. To keep a week's worth of snapshots, the user destroys the oldest
snapshot, renames the remaining snapshots, and then creates a new snapshot, as follows:
# zfs destroy -r pool/users@7daysago
# zfs rename -r pool/users@6daysago @7daysago
# zfs rename -r pool/users@5daysago @6daysago
# zfs rename -r pool/users@4daysago @5daysago
# zfs rename -r pool/users@3daysago @4daysago
# zfs rename -r pool/users@2daysago @3daysago
# zfs rename -r pool/users@yesterday @2daysago
# zfs rename -r pool/users@today @yesterday
# zfs snapshot -r pool/users@today
Example 16 Setting sharenfs Property Options on a ZFS File System
The following commands show how to set sharenfs property options to enable rw access for a
set of IP addresses and to enable root access for system neo on the tank/home file system.
# zfs set sharenfs='rw=@123.123.0.0/16:[::1],root=neo' tank/home
If you are using DNS for host name resolution, specify the fully qualified hostname.
Example 17 Delegating ZFS Administration Permissions on a ZFS Dataset
The following example shows how to set permissions so that user cindys can create,
destroy, mount, and take snapshots on tank/cindys. The permissions on tank/cindys are
also displayed.
# zfs allow cindys create,destroy,mount,snapshot tank/cindys
# zfs allow tank/cindys
---- Permissions on tank/cindys --------------------------------------
Local+Descendent permissions:
user cindys create,destroy,mount,snapshot
Because the tank/cindys mount point permission is set to 755 by default, user cindys will
be unable to mount file systems under tank/cindys. Add an ACE similar to the following
syntax to provide mount point access:
# chmod A+user:cindys:add_subdirectory:allow /tank/cindys
Example 18 Delegating Create Time Permissions on a ZFS Dataset
The following example shows how to grant anyone in the group staff to create file systems
in tank/users. This syntax also allows staff members to destroy their own file systems,
but not destroy anyone else's file system. The permissions on tank/users are also
displayed.
# zfs allow staff create,mount tank/users
# zfs allow -c destroy tank/users
# zfs allow tank/users
---- Permissions on tank/users ---------------------------------------
Permission sets:
destroy
Local+Descendent permissions:
group staff create,mount
Example 19 Defining and Granting a Permission Set on a ZFS Dataset
The following example shows how to define and grant a permission set on the tank/users
file system. The permissions on tank/users are also displayed.
# zfs allow -s @pset create,destroy,snapshot,mount tank/users
# zfs allow staff @pset tank/users
# zfs allow tank/users
---- Permissions on tank/users ---------------------------------------
Permission sets:
@pset create,destroy,mount,snapshot
Local+Descendent permissions:
group staff @pset
Example 20 Delegating Property Permissions on a ZFS Dataset
The following example shows to grant the ability to set quotas and reservations on the
users/home file system. The permissions on users/home are also displayed.
# zfs allow cindys quota,reservation users/home
# zfs allow users/home
---- Permissions on users/home ---------------------------------------
Local+Descendent permissions:
user cindys quota,reservation
cindys% zfs set quota=10G users/home/marks
cindys% zfs get quota users/home/marks
NAME PROPERTY VALUE SOURCE
users/home/marks quota 10G local
Example 21 Removing ZFS Delegated Permissions on a ZFS Dataset
The following example shows how to remove the snapshot permission from the staff group on
the tank/users file system. The permissions on tank/users are also displayed.
# zfs unallow staff snapshot tank/users
# zfs allow tank/users
---- Permissions on tank/users ---------------------------------------
Permission sets:
@pset create,destroy,mount,snapshot
Local+Descendent permissions:
group staff @pset
Example 22 Showing the differences between a snapshot and a ZFS Dataset
The following example shows how to see what has changed between a prior snapshot of a ZFS
dataset and its current state. The -F option is used to indicate type information for the
files affected.
# zfs diff -F tank/test@before tank/test
M / /tank/test/
M F /tank/test/linked (+1)
R F /tank/test/oldname -> /tank/test/newname
- F /tank/test/deleted
+ F /tank/test/created
M F /tank/test/modified
Example 23 Creating a bookmark
The following example create a bookmark to a snapshot. This bookmark can then be used
instead of snapshot in send streams.
# zfs bookmark rpool@snapshot rpool#bookmark
Example 24 Setting sharesmb Property Options on a ZFS File System
The following example show how to share SMB filesystem through ZFS. Note that that a user
and his/her password must be given.
# smbmount //127.0.0.1/share_tmp /mnt/tmp \
-o user=workgroup/turbo,password=obrut,uid=1000
Minimal /etc/samba/smb.conf configuration required:
Samba will need to listen to 'localhost' (127.0.0.1) for the ZFS utilities to communicate
with Samba. This is the default behavior for most Linux distributions.
Samba must be able to authenticate a user. This can be done in a number of ways, depending
on if using the system password file, LDAP or the Samba specific smbpasswd file. How to do
this is outside the scope of this manual. Please refer to the smb.conf(5) man page for
more information.
See the USERSHARE section of the smb.conf(5) man page for all configuration options in
case you need to modify any options to the share afterwards. Do note that any changes done
with the net(8) command will be undone if the share is ever unshared (such as at a reboot
etc).
INTERFACE STABILITY
Committed.
SEE ALSO
attr(1), gzip(1), ssh(1), chmod(2), fsync(2), stat(2), write(2), acl(5), attributes(5),
exports(5), exportfs(8), mount(8), net(8), selinux(8), zfs-program(8), zpool(8)