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NAME

       zfs - configures ZFS file systems

SYNOPSIS

       zfs [-?]

       zfs create [-p] [-o property=value] ... filesystem

       zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume

       zfs destroy [-rRf] filesystem|volume

       zfs destroy [-rRd] snapshot

       zfs snapshot [-r] [-o property=value]...
             filesystem@snapname|volume@snapname

       zfs rollback [-rRf] snapshot

       zfs clone [-p] [-o property=value] ... snapshot filesystem|volume

       zfs promote clone-filesystem

       zfs rename filesystem|volume|snapshot
            filesystem|volume|snapshot

       zfs rename [-p] filesystem|volume filesystem|volume

       zfs rename -r snapshot snapshot

       zfs list [-r|-d depth][-H][-o property[,...]] [-t type[,...]]
            [-s property] ... [-S property] ... [filesystem|volume|snapshot] ...

       zfs set property=value filesystem|volume|snapshot ...

       zfs get [-r|-d depth][-Hp][-o all | field[,...]] [-s source[,...]]
            all | property[,...] filesystem|volume|snapshot ...

       zfs inherit [-rS] property filesystem|volume|snapshot ...

       zfs upgrade [-v]

       zfs upgrade [-r] [-V version] -a | filesystem

       zfs userspace [-niHp] [-o field[,...]] [-sS field] ...
            [-t type [,...]] filesystem|snapshot

       zfs groupspace [-niHp] [-o field[,...]] [-sS field] ...
            [-t type [,...]] filesystem|snapshot

       zfs mount

       zfs mount [-vO] [-o options] -a | filesystem

       zfs unmount [-f] -a | filesystem|mountpoint

       zfs share -a | filesystem

       zfs unshare -a filesystem|mountpoint

       zfs send [-DvRp] [-[iI] snapshot] snapshot

       zfs receive [-vnFu] filesystem|volume|snapshot

       zfs receive [-vnFu] [-d | -e] filesystem

       zfs allow filesystem|volume

       zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...]
            filesystem|volume

       zfs allow [-ld] -e perm|@setname[,...] filesystem|volume

       zfs allow -c perm|@setname[,...] filesystem|volume

       zfs allow -s @setname perm|@setname[,...] filesystem|volume

       zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[,... ]]
            filesystem|volume

       zfs unallow [-rld] -e [perm|@setname[,... ]] filesystem|volume

       zfs unallow [-r] -c [perm|@setname[ ... ]] filesystem|volume

       zfs unallow [-r] -s @setname [perm|@setname[,... ]] filesystem|volume

       zfs hold [-r] tag snapshot...

       zfs holds [-r] snapshot...

       zfs release [-r] tag snapshot...

DESCRIPTION

       The  zfs  command  configures  ZFS  datasets  within  a  ZFS storage pool, as described in
       zpool(1M). 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).

       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 nonstandard 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  under  special  circumstances.  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.

   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(1M) command.

       See zpool(1M) 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, but
       cannot be accessed independently.

       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.

   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/vfstab 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/vfstab).  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/vfstab). 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.

   Zones
       A ZFS file system can be  added  to  a  non-global  zone  by  using  the  zonecfg  add  fs
       subcommand.  A ZFS file system that is added to a non-global zone must have its mountpoint
       property set to legacy.

       The  physical  properties  of  an  added  file  system  are  controlled  by   the   global
       administrator. However, the zone administrator can create, modify, or destroy files within
       the added file system, depending on how the file system is mounted.

       A dataset can also be delegated to a non-global zone by  using  the  zonecfg  add  dataset
       subcommand. You cannot delegate a dataset to one zone and the children of the same dataset
       to another zone. The zone administrator can change properties of the dataset or any of its
       children. However, the quota property is controlled by the global administrator.

       A ZFS volume can be added as a device to a non-global zone by using the zonecfg add device
       subcommand.  However,  its  physical  properties  can  be  modified  only  by  the  global
       administrator.

       For more information about zonecfg syntax, see zonecfg(1M).

       After  a  dataset  is  delegated to a non-global zone, the zoned property is automatically
       set. A  zoned  file  system  cannot  be  mounted  in  the  global  zone,  since  the  zone
       administrator might have to set the mount point to an unacceptable value.

       The global administrator can forcibly clear the zoned property, though this should be done
       with extreme care. The global administrator should verify that all the  mount  points  are
       acceptable before clearing the property.

   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.

   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

           The  compression  ratio  achieved  for  this  dataset,  expressed  as  a   multiplier.
           Compression  can  be turned on by running: zfs set compression=on dataset. The default
           value is off.

       creation

           The time this dataset was created.

       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.

       mounted

           For  file  systems,  indicates  whether  the  file  system  is currently mounted. This
           property can be either yes or no.

       origin

           For cloned file systems or volumes, the snapshot from which the clone was created. The
           origin cannot be destroyed (even with the -r or -f options) so long as a clone exists.

       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.

       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 are  freed  if  this  dataset  is
           recursively destroyed, is the greater of its space used and its reservation.

           When  snapshots  (see  the  "Snapshots" section) are created, their space is initially
           shared between the snapshot and the file system, and possibly with previous snapshots.
           As  the  file  system  changes, space that was previously shared becomes unique to the
           snapshot, and counted in the snapshot's space used. Additionally,  deleting  snapshots
           can increase the amount of space unique to (and used by) other snapshots.

           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(3c) 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:

               o      POSIX name (for example, joe)

               o      POSIX numeric ID (for example, 789)

               o      SID name (for example, joe.smith@mydomain)

               o      SID numeric ID (for example, S-1-123-456-789)

       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.

       volblocksize=blocksize

           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.

       The following native properties can be used to change the behavior of a ZFS dataset.

       aclinherit=discard | noallow | restricted | passthrough | passthrough-x

           Controls how ACL entries are inherited when files and directories are created. A  file
           system with an aclinherit property of discard does not inherit any ACL entries. A file
           system with an aclinherit property value of  noallow  only  inherits  inheritable  ACL
           entries  that  specify "deny" permissions. The property value restricted (the default)
           removes the write_acl and write_owner permissions when the ACL entry is  inherited.  A
           file  system with an aclinherit property value of passthrough inherits all inheritable
           ACL entries without any modifications made to the ACL entries when they are inherited.
           A  file system with an aclinherit property value of passthrough-x has the 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.

       aclmode=discard | groupmask | passthrough

           Controls  how  an  ACL  is  modified  during  chmod(2).  A file system with an aclmode
           property of discard deletes all ACL entries that do not  represent  the  mode  of  the
           file.   An  aclmode  property  of  groupmask  (the  default)  reduces  user  or  group
           permissions. The permissions are reduced, such that they are no greater than the group
           permission  bits,  unless it is a user entry that has the same UID as the owner of the
           file or directory. In this case, the ACL permissions are reduced so that they  are  no
           greater  than  owner  permission  bits.  A  file  system  with  an aclmode property of
           passthrough indicates that no changes are made to the ACL other  than  generating  the
           necessary ACL entries to represent the new mode of the file or directory.

       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 default value is on.

       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 the noauto option is set, 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

           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.
           Disabling checksums is NOT a recommended practice.

           Changing this property affects only newly-written data.

       compression=on | off | lzjb | gzip | gzip-N | zle

           Controls  the  compression  algorithm  used  for  this  dataset.  The lzjb compression
           algorithm is optimized  for  performance  while  providing  decent  data  compression.
           Setting  compression  to  on uses the lzjb compression algorithm. 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)).

           This  property can also be referred to by its shortened column name compress. Changing
           this property affects only newly-written data.

       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.

       dedup=on | off | verify | sha256[,verify]

           Controls  whether  deduplication is in effect for a dataset. The default value is off.
           The default checksum used for deduplication is sha256 (subject to change). When  dedup
           is  enabled, the dedup checksum algorithm overrides the checksum property. Setting the
           value to verify is equivalent to specifying sha256,verify.

           If the property is set to verify, then, whenever two blocks have the  same  signature,
           ZFS  will  do  a  byte-for-byte  comparison with the existing block to ensure that the
           contents are identical.

       devices=on | off

           Controls whether device nodes can be opened on this file system. The default value  is
           on.

       exec=on | off

           Controls  whether  processes can be executed from within this file system. The default
           value is on.

       mlslabel=label | none

           The mlslabel property is a sensitivity label that determines  if  a  dataset   can  be
           mounted  in a zone on a system with Trusted Extensions enabled. If the labeled dataset
           matches the labeled zone, the dataset can be mounted  and accessed  from  the  labeled
           zone.

           When  the  mlslabel  property  is  not  set,  the  default  value is none. Setting the
           mlslabel property to none is equivalent to removing the property.

           The mlslabel property can be modified only when Trusted Extensions is enabled and only
           with  appropriate  privilege. Rights to modify it cannot be delegated. When changing a
           label  to   a   higher   label   or   setting   the   initial   dataset   label,   the
           {PRIV_FILE_UPGRADE_SL}  privilege  is required. When changing a label to a lower label
           or the default (none), the {PRIV_FILE_DOWNGRADE_SL} privilege  is  required.  Changing
           the  dataset to labels other than the default can be done only when the dataset is not
           mounted. When a dataset with the default label is mounted  into  a  labeled-zone,  the
           mount operation automatically sets the mlslabel property to the label of that zone.

           When  Trusted  Extensions  is not enabled, only datasets with the default label (none)
           can be mounted.

       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 CIFS clients. Changes to this property only take effect when
           the file system is umounted and remounted.  See  mount(1M)  for  more  information  on
           nbmand 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.

       userquota@user=size | none

           Limits the amount of space consumed by the specified user.  Similar  to  the  refquota
           property,  the  userquota  space  calculation  does  not include space that is used by
           descendent  datasets,  such  as  snapshots  and  clones.  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 her quota before the system notices that  she  is  over  quota.  The
           system  would  then  begin 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:

               o      POSIX name (for example, joe)

               o      POSIX numeric ID (for example, 789)

               o      SID name (for example, joe.smith@mydomain)

               o      SID numeric ID (for example, S-1-123-456-789)

       groupquota@group=size | none

           Limits the amount of space consumed by the specified group. Group space consumption is
           identified by the userquota@user 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.

       readonly=on | off

           Controls whether this dataset can be modified. The default value is off.

           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.

           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.

       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

           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.

           This property can also be referred to by its shortened column name, refreserv.

       reservation=size | none

           The  minimum  amount  of  space  guaranteed to a dataset and 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 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 set-UID bit is respected for the file system. The  default  value
           is on.

       shareiscsi=on | off

           Like  the  sharenfs property, shareiscsi indicates whether a ZFS volume is exported as
           an iSCSI target. The acceptable values for this property are on, off,  and  type=disk.
           The  default  value  is off. In the future, other target types might be supported. For
           example, tape.

           You might want to set shareiscsi=on for a file system so that all ZFS  volumes  within
           the file system are shared by default. However, setting this property on a file system
           has no direct effect.

       sharesmb=on | off | opts

           Controls whether the file system is shared by using the Solaris CIFS service, and what
           options are to be used. A file system with the sharesmb property set to off is managed
           through traditional  tools  such  as  sharemgr(1M).  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 sharemgr(1M) command is invoked with no options. Otherwise,
           the  sharemgr(1M)  command  is invoked with options equivalent to the contents of this
           property.

           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 illegal in the resource  name,  are
           replaced  with  underscore  (_) characters. A pseudo property "name" is also supported
           that allows you to replace the data set name with a specified name. The specified name
           is then used to replace the prefix dataset in the case of inheritance. For example, if
           the dataset data/home/john is set to name=john, then  data/home/john  has  a  resource
           name  of john. If a child dataset of data/home/john/backups, it has a resource name of
           john_backups.

           When SMB shares are created, the SMB share name appears as an entry in the .zfs/shares
           directory.  You can use the ls or chmod command to display the share-level ACLs on the
           entries in this directory.

           When the sharesmb 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 set to off, or if they were shared before the property was changed. If  the
           new property is set to off, the file systems are unshared.

       sharenfs=on | off | opts

           Controls  whether the file system is shared via NFS, and what options are used. A file
           system with a sharenfs property of off is managed through traditional  tools  such  as
           share(1M),  unshare(1M),  and  dfstab(4).  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 share(1M) command is invoked with no options. Otherwise, the share(1M)
           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

           Provides  a  hint  to  ZFS  about handling of synchronous requests in this dataset. If
           logbias is set to  latency  (the  default),  ZFS  uses  the  pool's  log  devices  (if
           configured)  to  handle  the requests at low latency. If logbias is set to throughput,
           ZFS does not use the configured pool log devices. Instead, ZFS  optimizes  synchronous
           operations for global pool throughput and efficient use of resources.

       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.

       version=1 | 2 | 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 provisioning") can be
           created by specifying the -s option to the zfs create -V command, or by  changing  the
           reservation after the volume has been created. A "sparse volume" is a volume where the
           reservation is less then the volume size. 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 reservation.

       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.

       xattr=on | off

           Controls whether extended attributes are enabled for this  file  system.  The  default
           value is on.

       zoned=on | off

           Controls  whether  the  dataset  is  managed  from  a non-global zone. See the "Zones"
           section for more information. 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 Solaris CIFS server product. For more information about the
           mixed value behavior, see the Solaris 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(1M) 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
              devices                 devices/nodevices
              exec                    exec/noexec
              readonly                ro/rw
              setuid                  setuid/nosetuid
              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. Property names beginning with com.sun. are reserved for use by Sun Microsystems.

       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 1024 characters.

   ZFS Volumes as Swap or Dump Devices
       During an initial installation or a live upgrade from a UFS file system, a swap device and
       dump  device  are  created  on ZFS volumes in the ZFS root pool. By default, the swap area
       size is based on 1/2 the size of physical memory up to 2 Gbytes.  The  size  of  the  dump
       device  depends  on  the  kernel's requirements at installation time. Separate ZFS volumes
       must be used for the swap area and dump devices. Do not swap to  a  file  on  a  ZFS  file
       system. A ZFS swap file configuration is not supported.

       If  you  need  to  change  your  swap area or dump device after the system is installed or
       upgraded, use the swap(1M) and dumpadm(1M) commands. If you need to  change  the  size  of
       your swap area or dump device, see the Solaris ZFS Administration Guide.

SUBCOMMANDS

       All  subcommands  that  modify state are logged persistently to the pool in their original
       form.

       zfs ?

           Displays a help message.

       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.

           -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.

           -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.

       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/{dsk,rdsk}/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.

           -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.

           -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.

           -b blocksize

               Equivalent  to  -o  volblocksize=blocksize.  If  this  option  is   specified   in
               conjunction with -o volblocksize, the resulting behavior is undefined.

       zfs destroy [-rRf] 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 children.

           -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.

           Extreme  care  should  be taken when applying either the -r or the -f options, as they
           can destroy large portions of a pool and cause unexpected behavior  for  mounted  file
           systems in use.

       zfs destroy [-rRd] snapshot

           The  given  snapshot  is  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 the 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.

           -d

               Defer snapshot deletion.

           -r

               Destroy (or mark for deferred deletion) all snapshots with this name in descendent
               file systems.

           -R

               Recursively destroy all dependents.

       zfs snapshot [-r] [-o property=value] ... filesystem@snapname|volume@snapname

           Creates  a  snapshot  with  the  given  name. All previous modifications by successful
           system calls to the file system are part of the snapshot. See the "Snapshots"  section
           for details.

           -r

               Recursively  create  snapshots  of  all  descendent  datasets. Snapshots are taken
               atomically, so that all recursive snapshots correspond to the same moment in time.

           -o property=value

               Sets the specified property; see zfs create for details.

       zfs rollback [-rRf] 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
           must be destroyed by specifying the -r option.

           The -rR options do  not  recursively  destroy  the  child  snapshots  of  a  recursive
           snapshot.  Only  the  top-level  recursive  snapshot  is  destroyed by either of these
           options. To  completely  roll  back  a  recursive  snapshot,  you  must  rollback  the
           individual child snapshots.

           -r

               Recursively destroy any snapshots more recent than the one specified.

           -R

               Recursively  destroy  any  more  recent  snapshots, 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.

       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.

           -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.

           -o property=value

               Sets the specified property; see zfs create for details.

       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 filesystem|volume|snapshot
       filesystem|volume|snapshot
       zfs rename [-p] 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.

           -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] [-H] [-o property[,...]] [ -t type[,...]] [ -s property ] ... [ -S
       property ] ... [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.

           -r

               Recursively display any children of the dataset on the command line.

           -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:

                   o      One of the properties described in the "Native Properties" section

                   o      A user property

                   o      The value name to display the dataset name

                   o      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.

           -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 special 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:

                   o      Numeric types sort in numeric order.

                   o      String types sort in alphabetical order.

                   o      Types  inappropriate  for  a  row  sort that row to the literal bottom,
                          regardless of the specified ordering.

                   o      If no sorting options are specified the existing behavior of  zfs  list
                          is preserved.

           -S property

               Same as the -s option, but sorts by property in descending order.

           -t type

               A  comma-separated  list  of  types  to  display, where type is one of filesystem,
               snapshot , volume, or all. For  example,  specifying  -t  snapshot  displays  only
               snapshots.

       zfs set property=value filesystem|volume|snapshot ...

           Sets  the  property  to  the given value 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 all | field[,...] [-s source[,...]] all | property[,...]
       filesystem|volume|snapshot ...

           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. Can either be local, default,
                            temporary, inherited, or none (-).

           All columns except the RECEIVED column are displayed by default; specify particular or
           all  columns,  using  the  -o  option.  This  command  takes a comma-separated list of
           properties as described in the "Native Properties" and "User Properties" sections.

           The special value all can be used to display all properties that apply  to  the  given
           dataset's type (filesystem, volume, or snapshot).

           -r

               Recursively display properties for any children.

           -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.

           -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.

           -o field

               Set of fields to display. One or more of:

                 name,property,value,received,source

               Present multiple fields as a comma-separated list. The default value is:

                 name,property,value,source

               The keyword all specifies all sources.

           -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,none

               The default value is all sources.

           -p

               Display numbers in parseable (exact) values.

       zfs inherit [-rS] property filesystem|volume|snapshot ...

           Clears the specified property, causing it to be inherited  from  an  ancestor.  If  no
           ancestor  has  the  property set, then the default value is used. 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  to  the  received  property value, if any. If the property does not have a
               received value, the behavior of zfs inherit -S is the same as zfs inherit  without
               -S.  If  the  property  does have a received value, zfs inherit masks the received
               value with the inherited value until zfs inherit -S reverts to the received value.

       zfs upgrade [-v]

           Displays a list of file systems that are not the most recent version.

       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(1M)
           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.

           -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

           -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.

       zfs userspace [-niHp] [-o field[,...]] [-sS field]... [-t type [,...]] filesystem |
       snapshot

           Displays space consumed by, and quotas on, each user in the  specified  filesystem  or
           snapshot. This corresponds to the userused@user and userquota@user properties.

           -n

               Print numeric ID instead of user/group name.

           -H

               Do not print headers, use tab-delimited output.

           -p

               Use exact (parseable) numeric output.

           -o field[,...]

               Display only the specified fields from the following set, type,name,used,quota.The
               default is to display all fields.

           -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.

           -S field

               Sort by this field in reverse order. See -s.

           -t 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.

           -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 are 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.

       zfs groupspace [-niHp] [-o field[,...]] [-sS field]... [-t 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 mount

           Displays all ZFS file systems currently mounted.

       zfs mount [-vO] [-o options] -a | filesystem

           Mounts ZFS file systems. Invoked automatically as part of the boot process.

           -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.

           -O

               Perform an overlay mount. See mount(1M) for more information.

           -v

               Report mount progress.

           -a

               Mount all available ZFS file systems. Invoked automatically as part  of  the  boot
               process.

           filesystem

               Mount the specified filesystem.

       zfs unmount [-f] -a | filesystem|mountpoint

           Unmounts  currently  mounted  ZFS  file  systems. Invoked automatically as part of the
           shutdown process.

           -f

               Forcefully unmount the file system, even if it is currently in use.

           -a

               Unmount all available ZFS file systems. Invoked automatically as part of the  boot
               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.

       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. This is invoked automatically as  part  of
           the shutdown process.

           -a

               Unshare  all available ZFS file systems. Invoked automatically as part of the boot
               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 send [-DvRp] [-[iI] 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

               Perform dedup processing on the stream. Deduplicated streams cannot be received on
               systems that do not support the stream deduplication feature.

           -i snapshot

               Generate an incremental stream from the first snapshot to the second snapshot. The
               incremental  source (the first snapshot) can be specified as the last component of
               the snapshot name (for example, the part after the @), and it  is  assumed  to  be
               from the same file system as the second snapshot.

               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).

           -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 snapshot may be specified  as  with
               the -i option.

           -R

               Generate  a  replication  stream  package,  which  will  replicate  the  specified
               filesystem, 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.

           -p

               Send properties.

           -v

               Print verbose information about the stream package generated.

           The format of the stream is committed. You will be able to  receive  your  streams  on
           future versions of ZFS.

       zfs receive [-vnFu] filesystem|volume|snapshot
       zfs receive [-vnFu] [-d | -e] 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.

           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 -d or -e option.

           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  the  -d  or  -e  option  is
           specified,  the  snapshot  name is determined by appending the sent snapshot's name to
           the specified filesystem. If the -d option is specified, all but the pool name of  the
           sent  snapshot  path  is  appended  (for  example,  b/c@1  appended from sent snapshot
           a/b/c@1), and if the -e option is specified, only the tail of the sent  snapshot  path
           is appended (for example, c@1 appended from sent snapshot a/b/c@1). In the case of -d,
           any file systems needed to replicate the path of the sent snapshot are created  within
           the specified file system.

           -d

               Use all but the first element of the sent snapshot path (all but the pool name) to
               determine the name of the new snapshot as described in the paragraph above.

           -e

               Use the last element of the sent snapshot path to determine the name  of  the  new
               snapshot as described in the paragraph above.

           -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.

           -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.

           -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 -[iI]), destroy snapshots and file systems
               that do not exist on the sending side.

       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.

       zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...] filesystem| volume
       zfs allow [-ld] -e perm|@setname[,...] filesystem | volume

           Delegates ZFS administration permission for the file systems to non-privileged users.

           [-ug] "everyone"|user|group[,...]

               Specifies  to  whom  the  permissions  are  delegated.  Multiple  entities  can be
               specified as a comma-separated list. If neither of the -ug 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 -u or -g options. To specify a group with the same name as a
               user, use the -g options.

           [-e] perm|@setname[,...]

               Specifies that the permissions be delegated to  "everyone."  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  an  at  sign (@) , may be specified. See the -s form below for
               details.

           [-ld] filesystem|volume

               Specifies where the permissions are delegated. If neither of the -ld  options  are
               specified,  or  both  are, then the permissions are allowed for the file system or
               volume, and all of its descendents. If only the -l option is used, then is allowed
               "locally"  only for the specified file system. If only the -d option is used, then
               is allowed only for the descendent file systems.

       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
         destroy          subcommand     Must also have the 'mount' ability
         hold             subcommand     Allows adding a user hold to a snapshot
         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
         release          subcommand     Allows releasing a user hold which
                                         might destroy the snapshot
         rename           subcommand     Must also have the 'mount' and 'create'
                                         ability in the new parent
         rollback         subcommand
         send             subcommand
         share            subcommand     Allows sharing file systems over NFS or
                                         SMB protocols
         snapshot         subcommand
         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
         aclinherit       property
         aclmode          property
         atime            property
         canmount         property
         casesensitivity  property
         checksum         property
         compression      property
         copies           property
         dedup            property
         devices          property
         exec             property
         logbias          property
         mlslabel         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
         shareiscsi       property
         sharenfs         property
         sharesmb         property
         snapdir          property
         utf8only         property
         version          property
         volblocksize     property
         volsize          property
         vscan            property
         xattr            property
         zoned            property

       zfs allow -c 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[,...] 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 an "at
           sign" (@), and can be no more than 64 characters long.

       zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[, ...]] filesystem|volume
       zfs unallow [-rld] -e [perm|@setname [,...]] filesystem|volume
       zfs unallow [-r] -c [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[,...]]
       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 [-r] 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.

       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.

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(1M) 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              Mon Nov  9 15:05 2009  -
         pool/home/bob  used                  282M                   -
         pool/home/bob  available             134G                   -
         pool/home/bob  referenced            282M                   -
         pool/home/bob  compressratio         1.00x                  -
         pool/home/bob  mounted               yes                    -
         pool/home/bob  quota                 none                   default
         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  aclmode               groupmask              default
         pool/home/bob  aclinherit            restricted             default
         pool/home/bob  canmount              on                     default
         pool/home/bob  shareiscsi            off                    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         282M                   -
         pool/home/bob  usedbychildren        0                      -
         pool/home/bob  usedbyrefreservation  0                      -
         pool/home/bob  logbias               latency                default
         pool/home/bob  dedup                 off                    default
         pool/home/bob  mlslabel              none                   default

       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@aand 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 Creating a ZFS Volume as an iSCSI Target Device

       The following example shows how to create a ZFS volume as an iSCSI target.

         # zfs create -V 2g pool/volumes/vol1
         # zfs set shareiscsi=on pool/volumes/vol1
         # iscsitadm list target
         Target: pool/volumes/vol1
          iSCSI Name:
          iqn.1986-03.com.sun:02:7b4b02a6-3277-eb1b-e686-a24762c52a8c
          Connections: 0

       After  the iSCSI target is created, set up the iSCSI initiator. For more information about
       the Solaris iSCSI initiator, see iscsitadm(1M).

       Example 16 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@yesterday @5daysago
         # zfs rename -r pool/users@yesterday @4daysago
         # zfs rename -r pool/users@yesterday @3daysago
         # zfs rename -r pool/users@yesterday @2daysago
         # zfs rename -r pool/users@today @yesterday
         # zfs snapshot -r pool/users@today

       Example 17 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,root=neo' tank/home

       If you are using DNS for host name resolution, specify the fully qualified hostname.

       Example 18 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
         -------------------------------------------------------------
         Local+Descendent permissions on (tank/cindys)
                   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. Set an ACL  similar  to  the  following
       syntax to provide mount point access:

         # chmod A+user:cindys:add_subdirectory:allow /tank/cindys

       Example 19 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
         -------------------------------------------------------------
         Create time permissions on (tank/users)
                   create,destroy
         Local+Descendent permissions on (tank/users)
                   group staff create,mount
         -------------------------------------------------------------

       Example 20 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
         -------------------------------------------------------------
         Permission sets on (tank/users)
                 @pset create,destroy,mount,snapshot
         Create time permissions on (tank/users)
                 create,destroy
         Local+Descendent permissions on (tank/users)
                 group staff @pset,create,mount
         -------------------------------------------------------------

       Example 21 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
         -------------------------------------------------------------
         Local+Descendent permissions on (users/home)
                 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 22 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
         -------------------------------------------------------------
         Permission sets on (tank/users)
                 @pset create,destroy,mount,snapshot
         Create time permissions on (tank/users)
                 create,destroy
         Local+Descendent permissions on (tank/users)
                 group staff @pset,create,mount
         -------------------------------------------------------------

EXIT STATUS

       The following exit values are returned:

       0

           Successful completion.

       1

           An error occurred.

       2

           Invalid command line options were specified.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       ┌─────────────────────────────┬─────────────────────────────┐
       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
       ├─────────────────────────────┼─────────────────────────────┤
       │Availability                 │SUNWzfsu                     │
       ├─────────────────────────────┼─────────────────────────────┤
       │Interface Stability          │Committed                    │
       └─────────────────────────────┴─────────────────────────────┘

SEE ALSO

       ssh(1),  iscsitadm(1M),  mount(1M),  share(1M),  sharemgr(1M),  unshare(1M),  zonecfg(1M),
       zpool(1M), chmod(2), stat(2), write(2), fsync(3C), dfstab(4), attributes(5)

       See the gzip(1) man page, which is not part of the SunOS man page collection.

       For information about using the ZFS web-based management tool and other ZFS features,  see
       the Solaris ZFS Administration Guide.