Provided by: zfsutils-linux_0.6.5.6-0ubuntu30_amd64 
NAME
zpool - configures ZFS storage pools
SYNOPSIS
zpool [-?]
zpool add [-fgLnP] [-o property=value] pool vdev ...
zpool attach [-f] [-o property=value] pool device new_device
zpool clear pool [device]
zpool create [-fnd] [-o property=value] ... [-O file-system-property=value]
... [-m mountpoint] [-R root] [-t tname] pool vdev ...
zpool destroy [-f] pool
zpool detach pool device
zpool events [-vHfc] [pool] ...
zpool export [-a] [-f] pool ...
zpool get [-pH] "all" | property[,...] pool ...
zpool history [-il] [pool] ...
zpool import [-d dir] [-D]
zpool import [-o mntopts] [-o property=value] ... [-d dir | -c cachefile]
[-D] [-f] [-m] [-N] [-R root] [-F [-n] [-X] [-T]] -a
zpool import [-o mntopts] [-o property=value] ... [-d dir | -c cachefile]
[-D] [-f] [-m] [-R root] [-F [-n] [-X] [-T]] [-t]] pool |id [newpool]
zpool iostat [-T d | u ] [-gLPvy] [pool] ... [interval[count]]
zpool labelclear [-f] device
zpool list [-T d | u ] [-HgLPv] [-o property[,...]] [pool] ...
[interval[count]]
zpool offline [-t] pool device ...
zpool online pool device ...
zpool reguid pool
zpool reopen pool
zpool remove pool device ...
zpool replace [-f] [-o property=value] pool device [new_device]
zpool scrub [-s] pool ...
zpool set property=value pool
zpool split [-gLnP] [-R altroot] [-o property=value] pool newpool [device ...]
zpool status [-gLPvxD] [-T d | u] [pool] ... [interval [count]]
zpool upgrade
zpool upgrade -v
zpool upgrade [-V version] -a | pool ...
DESCRIPTION
The zpool command configures ZFS storage pools. A storage pool is a collection of devices
that provides physical storage and data replication for ZFS datasets.
All datasets within a storage pool share the same space. See zfs(8) for information on
managing datasets.
Virtual Devices (vdevs)
A "virtual device" describes a single device or a collection of devices organized
according to certain performance and fault characteristics. The following virtual devices
are supported:
disk A block device, typically located under /dev. ZFS can use individual partitions,
though the recommended mode of operation is to use whole disks. A disk can be
specified by a full path, or it can be a shorthand name (the relative portion of
the path under "/dev"). For example, "sda" is equivalent to "/dev/sda". A whole
disk can be specified by omitting the partition designation. When given a whole
disk, ZFS automatically labels the disk, if necessary.
file A regular file. The use of files as a backing store is strongly discouraged. It
is designed primarily for experimental purposes, as the fault tolerance of a
file is only as good as the file system of which it is a part. A file must be
specified by a full path.
mirror A mirror of two or more devices. Data is replicated in an identical fashion
across all components of a mirror. A mirror with N disks of size X can hold X
bytes and can withstand (N-1) devices failing before data integrity is
compromised.
raidz A variation on RAID-5 that allows for better distribution of parity and
raidz1 eliminates the "RAID-5 write hole" (in which data and parity become inconsistent
raidz2 after a power loss). Data and parity is striped across all disks within a raidz
raidz3 group.
A raidz group can have single-, double- , or triple parity, meaning that the
raidz group can sustain one, two, or three failures, respectively, without
losing any data. The raidz1 vdev type specifies a single-parity raidz group; the
raidz2 vdev type specifies a double-parity raidz group; and the raidz3 vdev type
specifies a triple-parity raidz group. The raidz vdev type is an alias for
raidz1.
A raidz group with N disks of size X with P parity disks can hold approximately
(N-P)*X bytes and can withstand P device(s) failing before data integrity is
compromised. The minimum number of devices in a raidz group is one more than the
number of parity disks. The recommended number is between 3 and 9 to help
increase performance.
spare A special pseudo-vdev which keeps track of available hot spares for a pool. For
more information, see the "Hot Spares" section.
log A separate-intent log device. If more than one log device is specified, then
writes are load-balanced between devices. Log devices can be mirrored. However,
raidz vdev types are not supported for the intent log. For more information, see
the "Intent Log" section.
cache A device used to cache storage pool data. A cache device cannot be configured as
a mirror or raidz group. For more information, see the "Cache Devices" section.
Virtual devices cannot be nested, so a mirror or raidz virtual device can only contain
files or disks. Mirrors of mirrors (or other combinations) are not allowed.
A pool can have any number of virtual devices at the top of the configuration (known as
"root vdevs"). Data is dynamically distributed across all top-level devices to balance
data among devices. As new virtual devices are added, ZFS automatically places data on the
newly available devices.
Virtual devices are specified one at a time on the command line, separated by whitespace.
The keywords "mirror" and "raidz" are used to distinguish where a group ends and another
begins. For example, the following creates two root vdevs, each a mirror of two disks:
# zpool create mypool mirror sda sdb mirror sdc sdd
Device Failure and Recovery
ZFS supports a rich set of mechanisms for handling device failure and data corruption. All
metadata and data is checksummed, and ZFS automatically repairs bad data from a good copy
when corruption is detected.
In order to take advantage of these features, a pool must make use of some form of
redundancy, using either mirrored or raidz groups. While ZFS supports running in a non-
redundant configuration, where each root vdev is simply a disk or file, this is strongly
discouraged. A single case of bit corruption can render some or all of your data
unavailable.
A pool's health status is described by one of three states: online, degraded, or faulted.
An online pool has all devices operating normally. A degraded pool is one in which one or
more devices have failed, but the data is still available due to a redundant
configuration. A faulted pool has corrupted metadata, or one or more faulted devices, and
insufficient replicas to continue functioning.
The health of the top-level vdev, such as mirror or raidz device, is potentially impacted
by the state of its associated vdevs, or component devices. A top-level vdev or component
device is in one of the following states:
DEGRADED One or more top-level vdevs is in the degraded state because one or more
component devices are offline. Sufficient replicas exist to continue
functioning.
One or more component devices is in the degraded or faulted state, but
sufficient replicas exist to continue functioning. The underlying conditions
are as follows:
o The number of checksum errors exceeds acceptable levels and the
device is degraded as an indication that something may be wrong.
ZFS continues to use the device as necessary.
o The number of I/O errors exceeds acceptable levels. The device
could not be marked as faulted because there are insufficient
replicas to continue functioning.
FAULTED One or more top-level vdevs is in the faulted state because one or more
component devices are offline. Insufficient replicas exist to continue
functioning.
One or more component devices is in the faulted state, and insufficient
replicas exist to continue functioning. The underlying conditions are as
follows:
o The device could be opened, but the contents did not match expected
values.
o The number of I/O errors exceeds acceptable levels and the device
is faulted to prevent further use of the device.
OFFLINE The device was explicitly taken offline by the "zpool offline" command.
ONLINE The device is online and functioning.
REMOVED The device was physically removed while the system was running. Device removal
detection is hardware-dependent and may not be supported on all platforms.
UNAVAIL The device could not be opened. If a pool is imported when a device was
unavailable, then the device will be identified by a unique identifier instead
of its path since the path was never correct in the first place.
If a device is removed and later re-attached to the system, ZFS attempts to put the device
online automatically. Device attach detection is hardware-dependent and might not be
supported on all platforms.
Hot Spares
ZFS allows devices to be associated with pools as "hot spares". These devices are not
actively used in the pool, but when an active device fails, it is automatically replaced
by a hot spare. To create a pool with hot spares, specify a "spare" vdev with any number
of devices. For example,
# zpool create pool mirror sda sdb spare sdc sdd
Spares can be shared across multiple pools, and can be added with the "zpool add" command
and removed with the "zpool remove" command. Once a spare replacement is initiated, a new
"spare" vdev is created within the configuration that will remain there until the original
device is replaced. At this point, the hot spare becomes available again.
If a pool has a shared spare that is currently being used, the pool can not be exported
since other pools may use this shared spare, which may lead to potential data corruption.
An in-progress spare replacement can be cancelled by detaching the hot spare. If the
original faulted device is detached, then the hot spare assumes its place in the
configuration, and is removed from the spare list of all active pools.
Spares cannot replace log devices.
Intent Log
The ZFS Intent Log (ZIL) satisfies POSIX requirements for synchronous transactions. For
instance, databases often require their transactions to be on stable storage devices when
returning from a system call. NFS and other applications can also use fsync() to ensure
data stability. By default, the intent log is allocated from blocks within the main pool.
However, it might be possible to get better performance using separate intent log devices
such as NVRAM or a dedicated disk. For example:
# zpool create pool sda sdb log sdc
Multiple log devices can also be specified, and they can be mirrored. See the EXAMPLES
section for an example of mirroring multiple log devices.
Log devices can be added, replaced, attached, detached, and imported and exported as part
of the larger pool. Mirrored log devices can be removed by specifying the top-level mirror
for the log.
Cache Devices
Devices can be added to a storage pool as "cache devices." These devices provide an
additional layer of caching between main memory and disk. For read-heavy workloads, where
the working set size is much larger than what can be cached in main memory, using cache
devices allow much more of this working set to be served from low latency media. Using
cache devices provides the greatest performance improvement for random read-workloads of
mostly static content.
To create a pool with cache devices, specify a "cache" vdev with any number of devices.
For example:
# zpool create pool sda sdb cache sdc sdd
Cache devices cannot be mirrored or part of a raidz configuration. If a read error is
encountered on a cache device, that read I/O is reissued to the original storage pool
device, which might be part of a mirrored or raidz configuration.
The content of the cache devices is considered volatile, as is the case with other system
caches.
Properties
Each pool has several properties associated with it. Some properties are read-only
statistics while others are configurable and change the behavior of the pool. The
following are read-only properties:
available Amount of storage available within the pool. This property can also be
referred to by its shortened column name, "avail".
capacity Percentage of pool space used. This property can also be referred to
by its shortened column name, "cap".
expandsize Amount of uninitialized space within the pool or device that can be
used to increase the total capacity of the pool. Uninitialized space
consists of any space on an EFI labeled vdev which has not been
brought online (i.e. zpool online -e). This space occurs when a LUN
is dynamically expanded.
fragmentation The amount of fragmentation in the pool.
free The amount of free space available in the pool.
freeing After a file system or snapshot is destroyed, the space it was using
is returned to the pool asynchronously. freeing is the amount of space
remaining to be reclaimed. Over time freeing will decrease while free
increases.
health The current health of the pool. Health can be "ONLINE", "DEGRADED",
"FAULTED", " OFFLINE", "REMOVED", or "UNAVAIL".
guid A unique identifier for the pool.
size Total size of the storage pool.
unsupported@feature_guid
Information about unsupported features that are enabled on the pool.
See zpool-features(5) for details.
used Amount of storage space used within the pool.
The space usage properties report actual physical space available to the storage pool. The
physical space can be different from the total amount of space that any contained datasets
can actually use. The amount of space used in a raidz configuration depends on the
characteristics of the data being written. In addition, ZFS reserves some space for
internal accounting that the zfs(8) command takes into account, but the zpool command does
not. For non-full pools of a reasonable size, these effects should be invisible. For small
pools, or pools that are close to being completely full, these discrepancies may become
more noticeable.
The following property can be set at creation time:
ashift
Pool sector size exponent, to the power of 2 (internally referred to as "ashift"). I/O
operations will be aligned to the specified size boundaries. Additionally, the minimum
(disk) write size will be set to the specified size, so this represents a space vs.
performance trade-off. The typical case for setting this property is when performance
is important and the underlying disks use 4KiB sectors but report 512B sectors to the
OS (for compatibility reasons); in that case, set ashift=12 (which is 1<<12 = 4096).
For optimal performance, the pool sector size should be greater than or equal to the
sector size of the underlying disks. Since the property cannot be changed after pool
creation, if in a given pool, you ever want to use drives that report 4KiB sectors,
you must set ashift=12 at pool creation time.
Keep in mind is that the ashift is vdev specific and is not a pool global. This means
that when adding new vdevs to an existing pool you may need to specify the ashift.
The following property can be set at creation time and import time:
altroot
Alternate root directory. If set, this directory is prepended to any mount points
within the pool. This can be used when examining an unknown pool where the mount
points cannot be trusted, or in an alternate boot environment, where the typical paths
are not valid. altroot is not a persistent property. It is valid only while the system
is up. Setting altroot defaults to using cachefile=none, though this may be overridden
using an explicit setting.
The following property can only be set at import time:
readonly=on | off
If set to on, the pool will be imported in read-only mode: Synchronous data in the
intent log will not be accessible, properties of the pool can not be changed and
datasets of the pool can only be mounted read-only. The readonly property of its
datasets will be implicitly set to on.
It can also be specified by its column name of rdonly.
To write to a read-only pool, a export and import of the pool is required.
The following properties can be set at creation time and import time, and later changed
with the zpool set command:
autoexpand=on | off
Controls automatic pool expansion when the underlying LUN is grown. If set to on, the
pool will be resized according to the size of the expanded device. If the device is
part of a mirror or raidz then all devices within that mirror/raidz group must be
expanded before the new space is made available to the pool. The default behavior is
off. This property can also be referred to by its shortened column name, expand.
autoreplace=on | off
Controls automatic device replacement. If set to "off", device replacement must be
initiated by the administrator by using the "zpool replace" command. If set to "on",
any new device, found in the same physical location as a device that previously
belonged to the pool, is automatically formatted and replaced. The default behavior is
"off". This property can also be referred to by its shortened column name, "replace".
bootfs=pool/dataset
Identifies the default bootable dataset for the root pool. This property is expected
to be set mainly by the installation and upgrade programs.
cachefile=path | none
Controls the location of where the pool configuration is cached. Discovering all pools
on system startup requires a cached copy of the configuration data that is stored on
the root file system. All pools in this cache are automatically imported when the
system boots. Some environments, such as install and clustering, need to cache this
information in a different location so that pools are not automatically imported.
Setting this property caches the pool configuration in a different location that can
later be imported with "zpool import -c". Setting it to the special value "none"
creates a temporary pool that is never cached, and the special value '' (empty string)
uses the default location.
Multiple pools can share the same cache file. Because the kernel destroys and
recreates this file when pools are added and removed, care should be taken when
attempting to access this file. When the last pool using a cachefile is exported or
destroyed, the file is removed.
comment=text
A text string consisting of printable ASCII characters that will be stored such that
it is available even if the pool becomes faulted. An administrator can provide
additional information about a pool using this property.
dedupditto=number
Threshold for the number of block ditto copies. If the reference count for a
deduplicated block increases above this number, a new ditto copy of this block is
automatically stored. The default setting is 0 which causes no ditto copies to be
created for deduplicated blocks. The miniumum legal nonzero setting is 100.
delegation=on | off
Controls whether a non-privileged user is granted access based on the dataset
permissions defined on the dataset. See zfs(8) for more information on ZFS delegated
administration.
failmode=wait | continue | panic
Controls the system behavior in the event of catastrophic pool failure. This condition
is typically a result of a loss of connectivity to the underlying storage device(s) or
a failure of all devices within the pool. The behavior of such an event is determined
as follows:
wait Blocks all I/O access until the device connectivity is recovered and the
errors are cleared. This is the default behavior.
continue Returns EIO to any new write I/O requests but allows reads to any of the
remaining healthy devices. Any write requests that have yet to be
committed to disk would be blocked.
panic Prints out a message to the console and generates a system crash dump.
feature@feature_name=enabled
The value of this property is the current state of feature_name. The only valid value
when setting this property is enabled which moves feature_name to the enabled state.
See zpool-features(5) for details on feature states.
listsnaps=on | off
Controls whether information about snapshots associated with this pool is output when
"zfs list" is run without the -t option. The default value is "off".
version=version
The current on-disk version of the pool. This can be increased, but never decreased.
The preferred method of updating pools is with the "zpool upgrade" command, though
this property can be used when a specific version is needed for backwards
compatibility. Once feature flags are enabled on a pool this property will no longer
have a value.
Subcommands
All subcommands that modify state are logged persistently to the pool in their original
form.
The zpool command provides subcommands to create and destroy storage pools, add capacity
to storage pools, and provide information about the storage pools. The following
subcommands are supported:
zpool -?
Displays a help message.
zpool add [-fgLnP] [-o property=value] pool vdev ...
Adds the specified virtual devices to the given pool. The vdev specification is
described in the "Virtual Devices" section. The behavior of the -f option, and the
device checks performed are described in the "zpool create" subcommand.
-f Forces use of vdevs, even if they appear in use or specify a conflicting
replication level. Not all devices can be overridden in this manner.
-g Display vdev GUIDs instead of the normal device names. These GUIDs can be used
in place of device names for the zpool detach/offline/remove/replace commands.
-L Display real paths for vdevs resolving all symbolic links. This can be used to
look up the current block device name regardless of the /dev/disk/ path used to
open it.
-n Displays the configuration that would be used without actually adding the vdevs.
The actual pool creation can still fail due to insufficient privileges or device
sharing.
-P Display full paths for vdevs instead of only the last component of the path.
This can be used in conjunction with the -L flag.
-o property=value
Sets the given pool properties. See the "Properties" section for a list of valid
properties that can be set. The only property supported at the moment is ashift.
Do note that some properties (among them ashift) are not inherited from a previous
vdev. They are vdev specific, not pool specific.
Do not add a disk that is currently configured as a quorum device to a zpool. After a
disk is in the pool, that disk can then be configured as a quorum device.
zpool attach [-f] [-o property=value] pool device new_device
Attaches new_device to an existing zpool device. The existing device cannot be part of
a raidz configuration. If device is not currently part of a mirrored configuration,
device automatically transforms into a two-way mirror of device and new_device. If
device is part of a two-way mirror, attaching new_device creates a three-way mirror,
and so on. In either case, new_device begins to resilver immediately.
-f Forces use of new_device, even if its appears to be in use. Not all devices can
be overridden in this manner.
-o property=value
Sets the given pool properties. See the "Properties" section for a list of valid
properties that can be set. The only property supported at the moment is "ashift".
zpool clear pool [device] ...
Clears device errors in a pool. If no arguments are specified, all device errors
within the pool are cleared. If one or more devices is specified, only those errors
associated with the specified device or devices are cleared.
zpool create [-fnd] [-o property=value] ... [-O file-system-property=value] ... [-m
mountpoint] [-R root] [-t tname] pool vdev ...
Creates a new storage pool containing the virtual devices specified on the command
line. The pool name must begin with a letter, and can only contain alphanumeric
characters as well as underscore ("_"), dash ("-"), period ("."), colon (":"), and
space (" "). The pool names "mirror", "raidz", "spare" and "log" are reserved, as are
names beginning with the pattern "c[0-9]". The vdev specification is described in the
"Virtual Devices" section.
The command verifies that each device specified is accessible and not currently in use
by another subsystem. There are some uses, such as being currently mounted, or
specified as the dedicated dump device, that prevents a device from ever being used by
ZFS. Other uses, such as having a preexisting UFS file system, can be overridden with
the -f option.
The command also checks that the replication strategy for the pool is consistent. An
attempt to combine redundant and non-redundant storage in a single pool, or to mix
disks and files, results in an error unless -f is specified. The use of differently
sized devices within a single raidz or mirror group is also flagged as an error unless
-f is specified.
Unless the -R option is specified, the default mount point is "/pool". The mount point
must not exist or must be empty, or else the root dataset cannot be mounted. This can
be overridden with the -m option.
By default all supported features are enabled on the new pool unless the -d option is
specified.
-f
Forces use of vdevs, even if they appear in use or specify a conflicting
replication level. Not all devices can be overridden in this manner.
-n
Displays the configuration that would be used without actually creating the pool.
The actual pool creation can still fail due to insufficient privileges or device
sharing.
-d
Do not enable any features on the new pool. Individual features can be enabled by
setting their corresponding properties to enabled with the -o option. See zpool-
features(5) for details about feature properties.
-o property=value [-o property=value] ...
Sets the given pool properties. See the "Properties" section for a list of valid
properties that can be set.
-O file-system-property=value
[-O file-system-property=value] ...
Sets the given file system properties in the root file system of the pool. See the
"Properties" section of zfs(8) for a list of valid properties that can be set.
-R root
Equivalent to "-o cachefile=none,altroot=root"
-m mountpoint
Sets the mount point for the root dataset. The default mount point is "/pool" or
"altroot/pool" if altroot is specified. The mount point must be an absolute path,
"legacy", or "none". For more information on dataset mount points, see zfs(8).
-t tname
Sets the in-core pool name to "tname" while the on-disk name will be the name
specified as the pool name "pool". This will set the default cachefile property to
none. This is intended to handle name space collisions when creating pools for
other systems, such as virtual machines or physical machines whose pools live on
network block devices.
zpool destroy [-f] pool
Destroys the given pool, freeing up any devices for other use. This command tries to
unmount any active datasets before destroying the pool.
-f Forces any active datasets contained within the pool to be unmounted.
zpool detach pool device
Detaches device from a mirror. The operation is refused if there are no other valid
replicas of the data. If device may be re-added to the pool later on then consider
the "zpool offline" command instead.
zpool events [-vHfc] [pool] ...
Description of the different events generated by the ZFS kernel modules. See zfs-
events(5) for more information about the subclasses and event payloads that can be
generated.
-v Get a full detail of the events and what information is available about it.
-H Scripted mode. Do not display headers, and separate fields by a single tab
instead of arbitrary space.
-f Follow mode.
-c Clear all previous events.
zpool export [-a] [-f] pool ...
Exports the given pools from the system. All devices are marked as exported, but are
still considered in use by other subsystems. The devices can be moved between systems
(even those of different endianness) and imported as long as a sufficient number of
devices are present.
Before exporting the pool, all datasets within the pool are unmounted. A pool can not
be exported if it has a shared spare that is currently being used.
For pools to be portable, you must give the zpool command whole disks, not just
partitions, so that ZFS can label the disks with portable EFI labels. Otherwise, disk
drivers on platforms of different endianness will not recognize the disks.
-a Exports all pools imported on the system.
-f Forcefully unmount all datasets, using the "unmount -f" command.
This command will forcefully export the pool even if it has a shared spare that
is currently being used. This may lead to potential data corruption.
zpool get [-p] "all" | property[,...] pool ...
Retrieves the given list of properties (or all properties if "all" is used) for the
specified storage pool(s). These properties are displayed with the following fields:
name Name of storage pool
property Property name
value Property value
source Property source, either 'default' or 'local'.
See the "Properties" section for more information on the available pool properties.
-p Display numbers in parseable (exact) values.
-H Scripted mode. Do not display headers, and separate fields by a single tab
instead of arbitrary space.
zpool history [-il] [pool] ...
Displays the command history of the specified pools or all pools if no pool is
specified.
-i Displays internally logged ZFS events in addition to user initiated events.
-l Displays log records in long format, which in addition to standard format
includes, the user name, the hostname, and the zone in which the operation was
performed.
zpool import [-d dir | -c cachefile] [-D]
Lists pools available to import. If the -d option is not specified, this command
searches for devices in "/dev". The -d option can be specified multiple times, and all
directories are searched. If the device appears to be part of an exported pool, this
command displays a summary of the pool with the name of the pool, a numeric
identifier, as well as the vdev layout and current health of the device for each
device or file. Destroyed pools, pools that were previously destroyed with the "zpool
destroy" command, are not listed unless the -D option is specified.
The numeric identifier is unique, and can be used instead of the pool name when
multiple exported pools of the same name are available.
-c cachefile Reads configuration from the given cachefile that was created with the
"cachefile" pool property. This cachefile is used instead of searching
for devices.
-d dir Searches for devices or files in dir. The -d option can be specified
multiple times.
-D Lists destroyed pools only.
zpool import [-o mntopts] [ -o property=value] ... [-d dir | -c cachefile] [-D] [-f] [-m]
[-N] [-R root] [-F [-n]] -a
Imports all pools found in the search directories. Identical to the previous command,
except that all pools with a sufficient number of devices available are imported.
Destroyed pools, pools that were previously destroyed with the "zpool destroy"
command, will not be imported unless the -D option is specified.
-o mntopts Comma-separated list of mount options to use when mounting
datasets within the pool. See zfs(8) for a description of dataset
properties and mount options.
-o property=value Sets the specified property on the imported pool. See the
"Properties" section for more information on the available pool
properties.
-c cachefile Reads configuration from the given cachefile that was created
with the "cachefile" pool property. This cachefile is used
instead of searching for devices.
-d dir Searches for devices or files in dir. The -d option can be
specified multiple times. This option is incompatible with the -c
option.
-D Imports destroyed pools only. The -f option is also required.
-f Forces import, even if the pool appears to be potentially active.
-F
Recovery mode for a non-importable pool. Attempt to return the
pool to an importable state by discarding the last few
transactions. Not all damaged pools can be recovered by using
this option. If successful, the data from the discarded
transactions is irretrievably lost. This option is ignored if the
pool is importable or already imported.
-a Searches for and imports all pools found.
-m
Allows a pool to import when there is a missing log device.
-R root Sets the "cachefile" property to "none" and the "altroot"
property to "root".
-N
Import the pool without mounting any file systems.
-n
Used with the -F recovery option. Determines whether a non-
importable pool can be made importable again, but does not
actually perform the pool recovery. For more details about pool
recovery mode, see the -F option, above.
-X
Used with the -F recovery option. Determines whether extreme
measures to find a valid txg should take place. This allows the
pool to be rolled back to a txg which is no longer guaranteed to
be consistent. Pools imported at an inconsistent txg may contain
uncorrectable checksum errors. For more details about pool
recovery mode, see the -F option, above. WARNING: This option
can be extremely hazardous to the health of your pool and should
only be used as a last resort.
-T
Specify the txg to use for rollback. Implies -FX. For more
details about pool recovery mode, see the -X option, above.
WARNING: This option can be extremely hazardous to the health of
your pool and should only be used as a last resort.
zpool import [-o mntopts] [ -o property=value] ... [-d dir | -c cachefile] [-D] [-f] [-m]
[-R root] [-F [-n]] [-t]] pool | id [newpool]
Imports a specific pool. A pool can be identified by its name or the numeric
identifier. If newpool is specified, the pool is imported using the name newpool.
Otherwise, it is imported with the same name as its exported name.
If a device is removed from a system without running "zpool export" first, the device
appears as potentially active. It cannot be determined if this was a failed export, or
whether the device is really in use from another host. To import a pool in this state,
the -f option is required.
-o mntopts
Comma-separated list of mount options to use when mounting datasets within the
pool. See zfs(8) for a description of dataset properties and mount options.
-o property=value
Sets the specified property on the imported pool. See the "Properties" section for
more information on the available pool properties.
-c cachefile
Reads configuration from the given cachefile that was created with the "cachefile"
pool property. This cachefile is used instead of searching for devices.
-d dir
Searches for devices or files in dir. The -d option can be specified multiple
times. This option is incompatible with the -c option.
-D
Imports destroyed pool. The -f option is also required.
-f
Forces import, even if the pool appears to be potentially active.
-F
Recovery mode for a non-importable pool. Attempt to return the pool to an
importable state by discarding the last few transactions. Not all damaged pools
can be recovered by using this option. If successful, the data from the discarded
transactions is irretrievably lost. This option is ignored if the pool is
importable or already imported.
-R root
Sets the "cachefile" property to "none" and the "altroot" property to "root".
-n
Used with the -F recovery option. Determines whether a non-importable pool can be
made importable again, but does not actually perform the pool recovery. For more
details about pool recovery mode, see the -F option, above.
-X
Used with the -F recovery option. Determines whether extreme measures to find a
valid txg should take place. This allows the pool to be rolled back to a txg
which is no longer guaranteed to be consistent. Pools imported at an inconsistent
txg may contain uncorrectable checksum errors. For more details about pool
recovery mode, see the -F option, above. WARNING: This option can be extremely
hazardous to the health of your pool and should only be used as a last resort.
-T
Specify the txg to use for rollback. Implies -FX. For more details about pool
recovery mode, see the -X option, above. WARNING: This option can be extremely
hazardous to the health of your pool and should only be used as a last resort.
-t
Used with "newpool". Specifies that "newpool" is temporary. Temporary pool names
last until export. Ensures that the original pool name will be used in all label
updates and therefore is retained upon export. Will also set -o cachefile=none
when not explicitly specified.
-m
Allows a pool to import when there is a missing log device.
zpool iostat [-T d | u] [-gLPvy] [pool] ... [interval[count]]
Displays I/O statistics for the given pools. When given an interval, the statistics
are printed every interval seconds until Ctrl-C is pressed. If no pools are specified,
statistics for every pool in the system is shown. If count is specified, the command
exits after count reports are printed.
-T u | d Display a time stamp.
Specify u for a printed representation of the internal representation of
time. See time(2). Specify d for standard date format. See date(1).
-g Display vdev GUIDs instead of the normal device names. These GUIDs can be
used in place of device names for the zpool detach/offline/remove/replace
commands.
-L Display real paths for vdevs resolving all symbolic links. This can be
used to look up the current block device name regardless of the /dev/disk/
path used to open it.
-P Display full paths for vdevs instead of only the last component of the
path. This can be used in conjunction with the -L flag.
-v Verbose statistics. Reports usage statistics for individual vdevs within
the pool, in addition to the pool-wide statistics.
-y Omit statistics since boot. Normally the first line of output reports the
statistics since boot. This option suppresses that first line of output.
zpool labelclear [-f] device
Removes ZFS label information from the specified device. The device must not be part
of an active pool configuration.
-f Treat exported or foreign devices as inactive.
zpool list [-T d | u] [-HgLPv] [-o props[,...]] [pool] ... [interval[count]]
Lists the given pools along with a health status and space usage. If no pools are
specified, all pools in the system are listed. When given an interval, the information
is printed every interval seconds until Ctrl-C is pressed. If count is specified, the
command exits after count reports are printed.
-H Scripted mode. Do not display headers, and separate fields by a single tab
instead of arbitrary space.
-g Display vdev GUIDs instead of the normal device names. These GUIDs can be
used in place of device names for the zpool detach/offline/remove/replace
commands.
-L Display real paths for vdevs resolving all symbolic links. This can be
used to look up the current block device name regardless of the /dev/disk/
path used to open it.
-P Display full paths for vdevs instead of only the last component of the
path. This can be used in conjunction with the -L flag.
-T d | u Display a time stamp.
Specify u for a printed representation of the internal representation of
time. See time(2). Specify d for standard date format. See date(1).
-o props Comma-separated list of properties to display. See the "Properties"
section for a list of valid properties. The default list is "name, size,
used, available, fragmentation, expandsize, capacity, dedupratio, health,
altroot"
-v Verbose statistics. Reports usage statistics for individual vdevs within
the pool, in addition to the pool-wise statistics.
zpool offline [-t] pool device ...
Takes the specified physical device offline. While the device is offline, no attempt
is made to read or write to the device.
This command is not applicable to spares or cache devices.
-t Temporary. Upon reboot, the specified physical device reverts to its previous
state.
zpool online [-e] pool device...
Brings the specified physical device online.
This command is not applicable to spares or cache devices.
-e Expand the device to use all available space. If the device is part of a mirror
or raidz then all devices must be expanded before the new space will become
available to the pool.
zpool reguid pool
Generates a new unique identifier for the pool. You must ensure that all devices in
this pool are online and healthy before performing this action.
zpool reopen pool
Reopen all the vdevs associated with the pool.
zpool remove pool device ...
Removes the specified device from the pool. This command currently only supports
removing hot spares, cache, and log devices. A mirrored log device can be removed by
specifying the top-level mirror for the log. Non-log devices that are part of a
mirrored configuration can be removed using the zpool detach command. Non-redundant
and raidz devices cannot be removed from a pool.
zpool replace [-f] [-o property=value] pool old_device [new_device]
Replaces old_device with new_device. This is equivalent to attaching new_device,
waiting for it to resilver, and then detaching old_device.
The size of new_device must be greater than or equal to the minimum size of all the
devices in a mirror or raidz configuration.
new_device is required if the pool is not redundant. If new_device is not specified,
it defaults to old_device. This form of replacement is useful after an existing disk
has failed and has been physically replaced. In this case, the new disk may have the
same /dev path as the old device, even though it is actually a different disk. ZFS
recognizes this.
-f Forces use of new_device, even if its appears to be in use. Not all devices can
be overridden in this manner.
-o property=value
Sets the given pool properties. See the "Properties" section for a list of valid
properties that can be set. The only property supported at the moment is ashift.
Do note that some properties (among them ashift) are not inherited from a
previous vdev. They are vdev specific, not pool specific.
zpool scrub [-s] pool ...
Begins a scrub. The scrub examines all data in the specified pools to verify that it
checksums correctly. For replicated (mirror or raidz) devices, ZFS automatically
repairs any damage discovered during the scrub. The "zpool status" command reports the
progress of the scrub and summarizes the results of the scrub upon completion.
Scrubbing and resilvering are very similar operations. The difference is that
resilvering only examines data that ZFS knows to be out of date (for example, when
attaching a new device to a mirror or replacing an existing device), whereas scrubbing
examines all data to discover silent errors due to hardware faults or disk failure.
Because scrubbing and resilvering are I/O-intensive operations, ZFS only allows one at
a time. If a scrub is already in progress, the "zpool scrub" command terminates it and
starts a new scrub. If a resilver is in progress, ZFS does not allow a scrub to be
started until the resilver completes.
-s Stop scrubbing.
zpool set property=value pool
Sets the given property on the specified pool. See the "Properties" section for more
information on what properties can be set and acceptable values.
zpool split [-gLnP] [-R altroot] [-o property=value] pool newpool [device ...]
Split devices off pool creating newpool. All vdevs in pool must be mirrors and the
pool must not be in the process of resilvering. At the time of the split, newpool will
be a replica of pool. By default, the last device in each mirror is split from pool to
create newpool.
The optional device specification causes the specified device(s) to be included in the
new pool and, should any devices remain unspecified, the last device in each mirror is
used as would be by default.
-g Display vdev GUIDs instead of the normal device names. These GUIDs can be used
in place of device names for the zpool detach/offline/remove/replace commands.
-L Display real paths for vdevs resolving all symbolic links. This can be used to
look up the current block device name regardless of the /dev/disk/ path used to
open it.
-n
Do dry run, do not actually perform the split. Print out the expected
configuration of newpool.
-P Display full paths for vdevs instead of only the last component of the path.
This can be used in conjunction with the -L flag.
-R altroot
Set altroot for newpool and automaticaly import it. This can be useful to avoid
mountpoint collisions if newpool is imported on the same filesystem as pool.
-o property=value
Sets the specified property for newpool. See the “Properties” section for more
information on the available pool properties.
zpool status [-gLPvxD] [-T d | u] [pool] ... [interval [count]]
Displays the detailed health status for the given pools. If no pool is specified, then
the status of each pool in the system is displayed. For more information on pool and
device health, see the "Device Failure and Recovery" section.
If a scrub or resilver is in progress, this command reports the percentage done and
the estimated time to completion. Both of these are only approximate, because the
amount of data in the pool and the other workloads on the system can change.
-g Display vdev GUIDs instead of the normal device names. These GUIDs can be
used innplace of device names for the zpool detach/offline/remove/replace
commands.
-L Display real paths for vdevs resolving all symbolic links. This can be
used to look up the current block device name regardless of the /dev/disk/
path used to open it.
-P Display full paths for vdevs instead of only the last component of the
path. This can be used in conjunction with the -L flag.
-v Displays verbose data error information, printing out a complete list of
all data errors since the last complete pool scrub.
-x Only display status for pools that are exhibiting errors or are otherwise
unavailable. Warnings about pools not using the latest on-disk format will
not be included.
-D Display a histogram of deduplication statistics, showing the allocated
(physically present on disk) and referenced (logically referenced in the
pool) block counts and sizes by reference count.
-T d | u Display a time stamp.
Specify u for a printed representation of the internal representation of
time. See time(2). Specify d for standard date format. See date(1).
zpool upgrade
Displays pools which do not have all supported features enabled and pools
formatted using a legacy ZFS version number. These pools can continue to be used,
but some features may not be available. Use "zpool upgrade -a" to enable all
features on all pools.
zpool upgrade -v
Displays legacy ZFS versions supported by the current software. See zfs-
features(5) for a description of feature flags features supported by the current
software.
zpool upgrade [-V version] -a | pool ...
Enables all supported features on the given pool. Once this is done, the pool will
no longer be accessible on systems that do not support feature flags. See zfs-
features(5) for details on compatibility with systems that support feature flags,
but do not support all features enabled on the pool.
-a Enables all supported features on all pools.
-V version Upgrade to the specified legacy version. If the -V flag is
specified, no features will be enabled on the pool. This option can
only be used to increase the version number up to the last supported
legacy version number.
EXAMPLES
Example 1 Creating a RAID-Z Storage Pool
The following command creates a pool with a single raidz root vdev that consists of six
disks.
# zpool create tank raidz sda sdb sdc sdd sde sdf
Example 2 Creating a Mirrored Storage Pool
The following command creates a pool with two mirrors, where each mirror contains two
disks.
# zpool create tank mirror sda sdb mirror sdc sdd
Example 3 Creating a ZFS Storage Pool by Using Partitions
The following command creates an unmirrored pool using two disk partitions.
# zpool create tank sda1 sdb2
Example 4 Creating a ZFS Storage Pool by Using Files
The following command creates an unmirrored pool using files. While not recommended, a
pool based on files can be useful for experimental purposes.
# zpool create tank /path/to/file/a /path/to/file/b
Example 5 Adding a Mirror to a ZFS Storage Pool
The following command adds two mirrored disks to the pool tank, assuming the pool is
already made up of two-way mirrors. The additional space is immediately available to any
datasets within the pool.
# zpool add tank mirror sda sdb
Example 6 Listing Available ZFS Storage Pools
The following command lists all available pools on the system. In this case, the pool zion
is faulted due to a missing device.
The results from this command are similar to the following:
# zpool list
NAME SIZE ALLOC FREE FRAG EXPANDSZ CAP DEDUP HEALTH ALTROOT
rpool 19.9G 8.43G 11.4G 33% - 42% 1.00x ONLINE -
tank 61.5G 20.0G 41.5G 48% - 32% 1.00x ONLINE -
zion - - - - - - - FAULTED -
Example 7 Destroying a ZFS Storage Pool
The following command destroys the pool tank and any datasets contained within.
# zpool destroy -f tank
Example 8 Exporting a ZFS Storage Pool
The following command exports the devices in pool tank so that they can be relocated or
later imported.
# zpool export tank
Example 9 Importing a ZFS Storage Pool
The following command displays available pools, and then imports the pool tank for use on
the system.
The results from this command are similar to the following:
# zpool import
pool: tank
id: 15451357997522795478
state: ONLINE
action: The pool can be imported using its name or numeric identifier.
config:
tank ONLINE
mirror ONLINE
sda ONLINE
sdb ONLINE
# zpool import tank
Example 10 Upgrading All ZFS Storage Pools to the Current Version
The following command upgrades all ZFS Storage pools to the current version of the
software.
# zpool upgrade -a
This system is currently running ZFS pool version 28.
Example 11 Managing Hot Spares
The following command creates a new pool with an available hot spare:
# zpool create tank mirror sda sdb spare sdc
If one of the disks were to fail, the pool would be reduced to the degraded state. The
failed device can be replaced using the following command:
# zpool replace tank sda sdd
Once the data has been resilvered, the spare is automatically removed and is made
available for use should another device fails. The hot spare can be permanently removed
from the pool using the following command:
# zpool remove tank sdc
Example 12 Creating a ZFS Pool with Mirrored Separate Intent Logs
The following command creates a ZFS storage pool consisting of two, two-way mirrors and
mirrored log devices:
# zpool create pool mirror sda sdb mirror sdc sdd log mirror \
sde sdf
Example 13 Adding Cache Devices to a ZFS Pool
The following command adds two disks for use as cache devices to a ZFS storage pool:
# zpool add pool cache sdc sdd
Once added, the cache devices gradually fill with content from main memory. Depending on
the size of your cache devices, it could take over an hour for them to fill. Capacity and
reads can be monitored using the iostat option as follows:
# zpool iostat -v pool 5
Example 14 Removing a Mirrored Log Device
The following command removes the mirrored log device mirror-2.
Given this configuration:
pool: tank
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
tank ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
sda ONLINE 0 0 0
sdb ONLINE 0 0 0
mirror-1 ONLINE 0 0 0
sdc ONLINE 0 0 0
sdd ONLINE 0 0 0
logs
mirror-2 ONLINE 0 0 0
sde ONLINE 0 0 0
sdf ONLINE 0 0 0
The command to remove the mirrored log mirror-2 is:
# zpool remove tank mirror-2
Example 15 Displaying expanded space on a device
The following command displays the detailed information for the data pool. This pool is
comprised of a single raidz vdev where one of its devices increased its capacity by 10GB.
In this example, the pool will not be able to utilized this extra capacity until all the
devices under the raidz vdev have been expanded.
# zpool list -v data
NAME SIZE ALLOC FREE FRAG EXPANDSZ CAP DEDUP HEALTH ALTROOT
data 23.9G 14.6G 9.30G 48% - 61% 1.00x ONLINE -
raidz1 23.9G 14.6G 9.30G 48% -
c1t1d0 - - - - -
c1t2d0 - - - - 10G
c1t3d0 - - - - -
EXIT STATUS
The following exit values are returned:
0 Successful completion.
1 An error occurred.
2 Invalid command line options were specified.
ENVIRONMENT VARIABLES
ZFS_ABORT
Cause zpool to dump core on exit for the purposes of running ::findleaks.
ZPOOL_IMPORT_PATH
The search path for devices or files to use with the pool. This is a colon-
separated list of directories in which zpool looks for device nodes and files.
Similar to the -d option in zpool import.
ZPOOL_VDEV_NAME_GUID
Cause zpool subcommands to output vdev guids by default. This behavior is
identical to the zpool status -g command line option.
ZPOOL_VDEV_NAME_FOLLOW_LINKS
Cause zpool subcommands to follow links for vdev names by default. This behavior
is identical to the zpool status -L command line option.
ZPOOL_VDEV_NAME_PATH
Cause zpool subcommands to output full vdev path names by default. This behavior
is identical to the zpool status -p command line option.
SEE ALSO
zfs(8), zpool-features(5), zfs-events(5)