zfs.8
| zfs(8) | System Administration Commands | zfs(8) |
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 [-fnpRrv] filesystem|volume
zfs destroy [-dnpRrv] filesystem|volume@snap[%snap][,...]
zfs destroy filesystem|volume#bookmark
zfs snapshot | snap [-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 [-f] filesystem|volume|snapshot
filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
zfs rename -r snapshot snapshot
zfs list [-r|-d depth][-Hp][-o property[,property]...] [-t type[,type]..]
[-s property] ... [-S property] ... [filesystem|volume|snapshot] ...
zfs set property=value filesystem|volume|snapshot ...
zfs get [-r|-d depth][-Hp][-o field[,...]] [-t type[,...]]
[-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 [-Hinp] [-o field[,...]] [-s field] ...
[-S field] ... [-t type[,...]] filesystem|snapshot
zfs groupspace [-Hinp] [-o field[,...]] [-s field] ...
[-S field] ... [-t type[,...]] filesystem|snapshot
zfs mount
zfs mount [-vO] [-o options] -a | filesystem
zfs unmount | umount [-f] -a | filesystem|mountpoint
zfs share -a | filesystem
zfs unshare -a filesystem|mountpoint
zfs bookmark snapshot bookmark
zfs send [-DnPpRveL] [-[iI] snapshot] snapshot
zfs send [-eL] [-i snapshot|bookmark] filesystem|volume|snapshot
zfs receive | recv [-vnFu] filesystem|volume|snapshot
zfs receive | recv [-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...
zfs diff [-FHt] snapshot snapshot|filesystem
DESCRIPTION
The zfs command configures ZFS datasets within a ZFS storage pool, as described in zpool(8). A dataset is identified by a unique path within the ZFS namespace. For example:
pool/{filesystem,volume,snapshot}
where the maximum length of a dataset name is MAXNAMELEN (256 bytes).
A dataset can be one of the following:
file system
volume
snapshot
bookmark
ZFS File System Hierarchy
A ZFS storage pool is a logical collection of devices that provide space for datasets. A storage pool is also the root of the ZFS file system hierarchy.
The root of the pool can be accessed as a file system, such as mounting and unmounting, taking snapshots, and setting properties. The physical storage characteristics, however, are managed by the zpool(8) command.
See zpool(8) for more information on creating and administering pools.
Snapshots
A snapshot is a read-only copy of a file system or volume. Snapshots can be created extremely quickly, and initially consume no additional space within the pool. As data within the active dataset changes, the snapshot consumes more data than would otherwise be shared with the active dataset.
Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back. Visibility is determined by the snapdev property of the parent volume.
File system snapshots can be accessed under the .zfs/snapshot directory in the root of the file system. Snapshots are automatically mounted on demand and may be unmounted at regular intervals. The visibility of the .zfs directory can be controlled by the snapdir property.
Bookmarks
A bookmark is like a snapshot, a read-only copy of a file system or volume. Bookmarks can be created extremely quickly, compared to snapshots, and they consume no additional space within the pool. Bookmarks can also have arbitrary names, much like snapshots.
Unlike snapshots, bookmarks can not be accessed through the filesystem in any way. From a storage standpoint a bookmark just provides a way to reference when a snapshot was created as a distinct object. Bookmarks are initially tied to a snapshot, not the filesystem/volume, and they will survive if the snapshot itself is destroyed. Since they are very light weight there's little incentive to destroy them.
Clones
A clone is a writable volume or file system whose initial contents are the same as another dataset. As with snapshots, creating a clone is nearly instantaneous, and initially consumes no additional space.
Clones can only be created from a snapshot. When a snapshot is cloned, it creates an implicit dependency between the parent and child. Even though the clone is created somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long as a clone exists. The origin property exposes this dependency, and the destroy command lists any such dependencies, if they exist.
The clone parent-child dependency relationship can be reversed by using the promote subcommand. This causes the "origin" file system to become a clone of the specified file system, which makes it possible to destroy the file system that the clone was created from.
Mount Points
Creating a ZFS file system is a simple operation, so the number of file systems per system is likely to be numerous. To cope with this, ZFS automatically manages mounting and unmounting file systems without the need to edit the /etc/fstab file. All automatically managed file systems are mounted by ZFS at boot time.
By default, file systems are mounted under /path, where path is the name of the file system in the ZFS namespace. Directories are created and destroyed as needed.
A file system can also have a mount point set in the mountpoint property. This directory is created as needed, and ZFS automatically mounts the file system when the zfs mount -a command is invoked (without editing /etc/fstab). The mountpoint property can be inherited, so if pool/home has a mount point of /export/stuff, then pool/home/user automatically inherits a mount point of /export/stuff/user.
A file system mountpoint property of none prevents the file system from being mounted.
If needed, ZFS file systems can also be managed with traditional tools (mount, umount, /etc/fstab). If a file system's mount point is set to legacy, ZFS makes no attempt to manage the file system, and the administrator is responsible for mounting and unmounting the file system.
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.
WARNING: DO NOT ENABLE DEDUPLICATION UNLESS YOU NEED IT AND KNOW EXACTLY WHAT YOU ARE DOING!
Deduplicating data is a very resource-intensive operation. It is generally recommended that you have at least 1.25 GB of RAM per 1 TB of storage when you enable deduplication. But calculating the exact requirenments is a somewhat complicated affair. Please see the Oracle Dedup Guide for more information..
Enabling deduplication on an improperly-designed system will result in extreme performance issues (extremely slow filesystem and snapshot deletions etc.) and can potentially lead to data loss (i.e. unimportable pool due to memory exhaustion) if your system is not built for this purpose. Deduplication affects the processing power (CPU), disks (and the controller) as well as primary (real) memory.
Before creating a pool with deduplication enabled, ensure that you have planned your hardware requirements appropriately and implemented appropriate recovery practices, such as regular backups.
Unless necessary, deduplication should NOT be enabled on a system. Instead, consider using compression=lz4, as a less resource-intensive alternative.
Native Properties
Properties are divided into two types, native properties and user-defined (or "user") properties. Native properties either export internal statistics or control ZFS behavior. In addition, native properties are either editable or read-only. User properties have no effect on ZFS behavior, but you can use them to annotate datasets in a way that is meaningful in your environment. For more information about user properties, see the "User Properties" section, below.
Every dataset has a set of properties that export statistics about the dataset as well as control various behaviors. Properties are inherited from the parent unless overridden by the child. Some properties apply only to certain types of datasets (file systems, volumes, or snapshots).
The values of numeric properties can be specified using human-readable suffixes (for example, k, KB, M, Gb, and so forth, up to Z for zettabyte). The following are all valid (and equal) specifications:
1536M, 1.5g, 1.50GB
The values of non-numeric properties are case sensitive and must be lowercase, except for mountpoint, sharenfs, and sharesmb.
The following native properties consist of read-only statistics about the dataset. These properties can be neither set, nor inherited. Native properties apply to all dataset types unless otherwise noted.
available
This property can also be referred to by its shortened column name, avail.
compressratio
creation
clones
defer_destroy
filesystem_count
logicalreferenced
This property can also be referred to by its shortened column name, lrefer.
logicalused
This property can also be referred to by its shortened column name, lused.
mounted
origin
referenced
This property can also be referred to by its shortened column name, refer.
refcompressratio
snapshot_count
type
used
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(2) or O_SYNC does not necessarily guarantee that the space usage information is updated immediately.
usedby*
usedbychildren
usedbydataset
usedbyrefreservation
usedbysnapshots
userused@user
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
groupused@group
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
This property can also be referred to by its shortened column name, volblock.
written
written@snapshot
The snapshot may be specified as a short snapshot name (just the part after the @), in which case it will be interpreted as a snapshot in the same filesystem as this dataset. The snapshot be a full snapshot name (filesystem@snapshot), which for clones may be a snapshot in the origin's filesystem (or the origin of the origin's filesystem, etc).
The following native properties can be used to change the behavior of a ZFS dataset.
aclinherit=discard | noallow | restricted | passthrough | passthrough-x
When the property value is set to passthrough, files are created with a mode determined by the inheritable ACEs. If no inheritable ACEs exist that affect the mode, then the mode is set in accordance to the requested mode from the application.
The aclinherit property does not apply to Posix ACLs.
acltype=noacl | posixacl
To obtain the best performance when setting posixacl users are strongly encouraged to set the xattr=sa property. This will result in the Posix ACL being stored more efficiently on disk. But as a consequence of this all new xattrs will only be accessible from ZFS implementations which support the xattr=sa property. See the xattr property for more details.
atime=on | off
canmount=on | off | noauto
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
Changing this property affects only newly-written data.
compression=on | off | lzjb | lz4 | gzip | gzip-N | zle
Setting compression to on indicates that the current default compression algorithm should be used. The default balances compression and decompression speed, with compression ratio and is expected to work well on a wide variety of workloads. Unlike all other settings for this property, on does not select a fixed compression type. As new compression algorithms are added to ZFS and enabled on a pool, the default compression algorithm may change. The current default compression algorthm is either lzjb or, if the lz4_compress feature is enabled, lz4.
The lzjb compression algorithm is optimized for performance while providing decent data compression.
The lz4 compression algorithm is a high-performance replacement for the lzjb algorithm. It features significantly faster compression and decompression, as well as a moderately higher compression ratio than lzjb, but can only be used on pools with the lz4_compress feature set to enabled. See zpool-features(5) for details on ZFS feature flags and the lz4_compress feature.
The gzip compression algorithm uses the same compression as the gzip(1) command. You can specify the gzip level by using the value gzip-N where N is an integer from 1 (fastest) to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6 (which is also the default for gzip(1)). The zle compression algorithm compresses runs of zeros.
This property can also be referred to by its shortened column name compress. Changing this property affects only newly-written data.
copies=1 | 2 | 3
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]
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.
Unless necessary, deduplication should NOT be enabled on a system. See Deduplication above.
devices=on | off
exec=on | off
mlslabel=label | none
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.
Zones are a Solaris feature and are not relevant on Linux.
filesystem_limit=count | none
mountpoint=path | none | legacy
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
primarycache=all | none | metadata
quota=size | none
Quotas cannot be set on volumes, as the volsize property acts as an implicit quota.
snapshot_limit=count | none
userquota@user=size | none
Enforcement of user quotas may be delayed by several seconds. This delay means that a user might exceed their quota before the system notices that they are over quota and begins to refuse additional writes with the EDQUOT error message . See the zfs userspace subcommand for more information.
Unprivileged users can only access their own groups' space usage. The root user, or a user who has been granted the userquota privilege with zfs allow, can get and set everyone's quota.
This property is not available on volumes, on file systems before version 4, or on pools before version 15. The userquota@... properties are not displayed by zfs get all. The user's name must be appended after the @ symbol, using one of the following forms:
- 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
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
This property can also be referred to by its shortened column name, rdonly.
recordsize=size
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.
redundant_metadata=all | most
When set to all, ZFS stores an extra copy of all metadata. If a single on-disk block is corrupt, at worst a single block of user data (which is recordsize bytes long) can be lost.
When set to most, ZFS stores an extra copy of most types of metadata. This can improve performance of random writes, because less metadata must be written. In practice, at worst about 100 blocks (of recordsize bytes each) of user data can be lost if a single on-disk block is corrupt. The exact behavior of which metadata blocks are stored redundantly may change in future releases.
The default value is all.
refquota=size | none
refreservation=size | none
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.
relatime=on | off
reservation=size | none
This property can also be referred to by its shortened column name, reserv.
secondarycache=all | none | metadata
setuid=on | off
shareiscsi=on | off
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
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. The ZFS On Linux driver does not (yet) support additional options which might be available in the Solaris version.
If the sharesmb property is set to off, the file systems are unshared.
In Linux, the share is created with the ACL (Access Control List) "Everyone:F" ("F" stands for "full permissions", ie. read and write permissions) and no guest access (which means samba must be able to authenticate a real user, system passwd/shadow, ldap or smbpasswd based) by default. This means that any additional access control (dissalow specific user specific access etc) must be done on the underlaying filesystem.
Example to mount a SMB filesystem shared through ZFS (share/tmp): Note that a
user and his/her password must be given!
smbmount //127.0.0.1/share_tmp /mnt/tmp -o
user=workgroup/turbo,password=obrut,uid=1000
Minimal /etc/samba/smb.conf configuration
* Samba will need to listen to 'localhost' (127.0.0.1) for the zfs utilities
to communitate with samba. This is the default behavior for most Linux
distributions.
* Samba must be able to authenticate a user. This can be done in a number of ways, depending on if using the system password file, LDAP or the Samba specific smbpasswd file. How to do this is outside the scope of this manual. Please refer to the smb.conf(5) manpage for more information.
* See the USERSHARE section of the smb.conf(5) man page for all configuration options in case you need to modify any options to the share afterwards. Do note that any changes done with the 'net' command will be undone if the share is every unshared (such as at a reboot etc). In the future, ZoL will be able to set specific options directly using sharesmb=<option>.
sharenfs=on | off | opts
/usr/sbin/exportfs -i -o sec=sys,rw,no_subtree_check,no_root_squash,mountpoint *:<mountpoint of dataset>
Otherwise, the exportfs(8) command is invoked with options equivalent to the contents of this property.
When the sharenfs property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously off, or if they were shared before the property was changed. If the new property is off, the file systems are unshared.
logbias = latency | throughput
snapdev=hidden | visible
snapdir=hidden | visible
sync=standard | always | disabled
version=1 | 2 | current
volsize=size
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
xattr=on | off | sa
The default value of on enables directory based extended attributes. This style of xattr imposes no practical limit on either the size or number of xattrs which may be set on a file. Although under Linux the getxattr(2) and setxattr(2) system calls limit the maximum xattr size to 64K. This is the most compatible style of xattr and it is supported by the majority of ZFS implementations.
System attribute based xattrs may be enabled by setting the value to sa. The key advantage of this type of xattr is improved performance. Storing xattrs as system attributes significantly decreases the amount of disk IO required. Up to 64K of xattr data may be stored per file in the space reserved for system attributes. If there is not enough space available for an xattr then it will be automatically written as a directory based xattr. System attribute based xattrs are not accessible on platforms which do not support the xattr=sa feature.
The use of system attribute based xattrs is strongly encouraged for users of SELinux or Posix ACLs. Both of these features heavily rely of xattrs and benefit significantly from the reduced xattr access time.
zoned=on | 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
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
utf8only=on | off
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.
context=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
fscontext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
defntext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
rootcontext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
overlay=on | off
Temporary Mount Point Properties
When a file system is mounted, either through mount(8) for legacy mounts or the zfs mount command for normal file systems, its mount options are set according to its properties. The correlation between properties and mount options is as follows:
PROPERTY MOUNT OPTION
devices devices/nodevices
exec exec/noexec
readonly ro/rw
setuid setuid/nosetuid
xattr xattr/noxattr
atime atime/noatime
relatime relatime/norelatime
nbmand nbmand/nonbmand
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. For example, property names beginning with com.sun. are reserved for use by Oracle Corporation (which acquired 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
ZFS volumes may be used as Linux swap devices. After creating the volume with the zfs create command set up and enable the swap area using the mkswap(8) and swapon(8) commands. Do not swap to a file on a ZFS file system. A ZFS swap file configuration is not supported.
SUBCOMMANDS
All subcommands that modify state are logged persistently to the pool in their original form.
zfs ?
zfs create [-p] [-o property=value] ... filesystem
-p
-o property=value
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
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
-s
-o property=value
-b blocksize
zfs destroy [-fnpRrv] filesystem|volume
-r
-R
-f
-n
-p
-v
Extreme care should be taken when applying either the -r or the -R options, as they can destroy large portions of a pool and cause unexpected behavior for mounted file systems in use.
zfs destroy [-dnpRrv] filesystem|volume@snap[%snap][,...]
If a snapshot does not qualify for immediate destruction, it is marked for deferred destruction. In this state, it exists as a usable, visible snapshot until both of the preconditions listed above are met, at which point it is destroyed.
An inclusive range of snapshots may be specified by separating the first and last snapshots with a percent sign. The first and/or last snapshots may be left blank, in which case the filesystem's oldest or newest snapshot will be implied.
Multiple snapshots (or ranges of snapshots) of the same filesystem or volume may be specified in a comma-separated list of snapshots. Only the snapshot's short name (the part after the @) should be specified when using a range or comma-separated list to identify multiple snapshots.
-d
-r
-R
-n
-p
-v
Extreme care should be taken when applying either the -r or the -R options, as they can destroy large portions of a pool and cause unexpected behavior for mounted file systems in use.
zfs destroy filesystem|volume#bookmark
zfs snapshot [-r] [-o property=value] ... filesystem@snapname|volume@snapname ...
-r
-o property=value
zfs rollback [-rRf] snapshot
The -rR options do not recursively destroy the child snapshots of a recursive snapshot. Only direct snapshots of the specified filesystem are destroyed by either of these options. To completely roll back a recursive snapshot, you must rollback the individual child snapshots.
-r
-R
-f
zfs clone [-p] [-o property=value] ... snapshot filesystem|volume
-p
-o property=value
zfs promote clone-filesystem
The snapshot that was cloned, and any snapshots previous to this snapshot, are now owned by the promoted clone. The space they use moves from the origin file system to the promoted clone, so enough space must be available to accommodate these snapshots. No new space is consumed by this operation, but the space accounting is adjusted. The promoted clone must not have any conflicting snapshot names of its own. The rename subcommand can be used to rename any conflicting snapshots.
zfs rename [-f]
filesystem|volume|snapshot
filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume
filesystem|volume
-p
-f
zfs rename -r snapshot snapshot
zfs list [-r|-d depth] [-Hp] [-o property[,...]] [ -t type[,...]] [ -s property ] ... [ -S property ] ... [filesystem|volume|snapshot] ...
-H
-p
-r
-d depth
-o property
- 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
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
-t type
zfs set property=value filesystem|volume|snapshot ...
zfs get [-r|-d depth] [-Hp] [-o field[,...] [-t type[,...]] [-s source[,...] "all" | property[,...] filesystem|volume|snapshot ...
name Dataset name
property Property name
value Property value
source Property source. Can either be local, default,
temporary, inherited, received, or none (-).
All columns are displayed by default, though this can be controlled by using the -o option. This command takes a comma-separated list of properties as described in the "Native Properties" and "User Properties" sections.
The special value all can be used to display all properties that apply to the given dataset's type (filesystem, volume snapshot, or bookmark).
-r
-d depth
-H
-o field
-s source
-p
zfs inherit [-rS] property filesystem|volume|snapshot ...
-r
-S
zfs upgrade [-v]
zfs upgrade [-r] [-V version] [-a | filesystem]
In general, the file system version is independent of the pool version. See zpool(8) for information on the zpool upgrade command.
In some cases, the file system version and the pool version are interrelated and the pool version must be upgraded before the file system version can be upgraded.
-a
filesystem
-r
-V version
zfs userspace [-Hinp] [-o field[,...]] [-s field] ... [-S field] ... [-t type[,...]] filesystem|snapshot
-n
-H
-p
-o field[,...]
-s field
-S field
-t type[,...]
-i
zfs groupspace [-Hinp] [-o field[,...]] [-s field] ... [-S field] ... [-t type[,...]] filesystem|snapshot
zfs mount
zfs mount [-vO] [-o options] -a | filesystem
-o options
-O
-v
-a
filesystem
zfs unmount [-f] -a | filesystem|mountpoint
-f
-a
filesystem|mountpoint
zfs share -a | filesystem
-a
filesystem
zfs unshare -a | filesystem|mountpoint
-a
filesystem|mountpoint
zfs bookmark snapshot bookmark
This feature must be enabled to be used. See zpool-features(5) for details on ZFS feature flags and the bookmarks feature.
zfs send [-DnPpRveL] [-[iI] snapshot] snapshot
-i 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
-R
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.
-D
-L
-e
-p
-n
-P
-v
The format of the stream is committed. You will be able to receive your streams on future versions of ZFS.
zfs send [-eL] [-i snapshot|bookmark] filesystem|volume|snapshot
-i snapshot|bookmark
If the incremental target is a clone, the incremental source can be the origin snapshot, or an earlier snapshot in the origin's filesystem, or the origin's origin, etc.
-L
-e
zfs receive [-vnFu]
filesystem|volume|snapshot
zfs receive [-vnFu] [-d|-e]
filesystem
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 use of the -d or -e options.
If the argument is a snapshot name, the specified snapshot is created. If the argument is a file system or volume name, a snapshot with the same name as the sent snapshot is created within the specified filesystem or volume. If neither of the -d or -e options are specified, the provided target snapshot name is used exactly as provided.
The -d and -e options cause the file system name of the target snapshot to be determined by appending a portion of the sent snapshot's name to the specified target filesystem. If the -d option is specified, all but the first element of the sent snapshot's file system path (usually the pool name) is used and any required intermediate file systems within the specified one are created. If the -e option is specified, then only the last element of the sent snapshot's file system name (i.e. the name of the source file system itself) is used as the target file system name.
-d
-e
-u
-v
-n
-F
zfs allow filesystem | volume
zfs allow [-ldug]
"everyone"|user|group[,...]
perm|@setname[,...] filesystem| volume
zfs allow [-ld] -e
perm|@setname[,...] filesystem | volume
[-ug] "everyone"|user|group[,...]
[-e] perm|@setname[,...]
[-ld] filesystem|volume
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 diff subcommand Allows lookup of paths within a dataset
given an object number, and the ability to
create snapshots necessary to 'zfs diff'. mount subcommand Allows mount/umount of ZFS datasets promote subcommand Must also have the 'mount'
and 'promote' ability in the origin file system receive subcommand Must also have the 'mount' and 'create' ability rename subcommand Must also have the 'mount' and 'create'
ability in the new parent rollback subcommand Must also have the 'mount' ability send subcommand share subcommand Allows sharing file systems over NFS or SMB
protocols snapshot subcommand Must also have the 'mount' ability groupquota other Allows accessing any groupquota@... property groupused other Allows reading any groupused@... property userprop other Allows changing any user property userquota other Allows accessing any userquota@... property userused other Allows reading any userused@... property acltype property aclinherit property atime property canmount property casesensitivity property checksum property compression property copies property dedup property devices property exec property filesystem_limit 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 snapshot_limit property utf8only property version property volblocksize property volsize property vscan property xattr property zoned property
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
-r
zfs unallow [-r] -s @setname
[perm|@setname[,...]]
filesystem|volume
zfs hold [-r] tag snapshot...
If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs destroy command return EBUSY.
-r
zfs holds [-r] snapshot...
-r
zfs release [-r] tag snapshot...
If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs destroy command return EBUSY.
-r
zfs diff [-FHt] snapshot snapshot|filesystem
The types of change are:
- The path has been removed + The path has been created M The path has been modified R The path has been renamed
-F
B Block device C Character device / Directory > Door | Named pipe @ Symbolic link P Event port = Socket F Regular file
-H
-t
EXAMPLES
Example 1 Creating a ZFS File System Hierarchy
The following commands create a file system named pool/home and a file system named pool/home/bob. The mount point /export/home is set for the parent file system, and is automatically inherited by the child file system.
# zfs create pool/home # zfs set mountpoint=/export/home pool/home # zfs create pool/home/bob
Example 2 Creating a ZFS Snapshot
The following command creates a snapshot named yesterday. This snapshot is mounted on demand in the .zfs/snapshot directory at the root of the pool/home/bob file system.
# zfs snapshot pool/home/bob@yesterday
Example 3 Creating and Destroying Multiple Snapshots
The following command creates snapshots named yesterday of pool/home and all of its descendent file systems. Each snapshot is mounted on demand in the .zfs/snapshot directory at the root of its file system. The second command destroys the newly created snapshots.
# zfs snapshot -r pool/home@yesterday # zfs destroy -r pool/home@yesterday
Example 4 Disabling and Enabling File System Compression
The following command disables the compression property for all file systems under pool/home. The next command explicitly enables compression for pool/home/anne.
# zfs set compression=off pool/home # zfs set compression=on pool/home/anne
Example 5 Listing ZFS Datasets
The following command lists all active file systems and volumes in the system. Snapshots are displayed if the listsnaps property is on. The default is off. See zpool(8) for more information on pool properties.
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
pool 450K 457G 18K /pool
pool/home 315K 457G 21K /export/home
pool/home/anne 18K 457G 18K /export/home/anne
pool/home/bob 276K 457G 276K /export/home/bob
Example 6 Setting a Quota on a ZFS File System
The following command sets a quota of 50 Gbytes for pool/home/bob.
# zfs set quota=50G pool/home/bob
Example 7 Listing ZFS Properties
The following command lists all properties for pool/home/bob.
# zfs get all pool/home/bob NAME PROPERTY VALUE SOURCE pool/home/bob type filesystem - pool/home/bob creation Tue Jul 21 15:53 2009 - pool/home/bob used 21K - pool/home/bob available 20.0G - pool/home/bob referenced 21K - pool/home/bob compressratio 1.00x - pool/home/bob mounted yes - pool/home/bob quota 20G local pool/home/bob reservation none default pool/home/bob recordsize 128K default pool/home/bob mountpoint /pool/home/bob default pool/home/bob sharenfs off default pool/home/bob checksum on default pool/home/bob compression on local pool/home/bob atime on default pool/home/bob devices on default pool/home/bob exec on default pool/home/bob setuid on default pool/home/bob readonly off default pool/home/bob zoned off default pool/home/bob snapdir hidden default pool/home/bob acltype off default pool/home/bob aclinherit restricted default pool/home/bob canmount on default pool/home/bob 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 21K - 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 pool/home/bob relatime off 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
The following command causes pool/home/bob to revert to the received value for the quota property if it exists.
# zfs inherit -S quota pool/home/bob
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@4daysago @5daysago # zfs rename -r pool/users@3daysago @4daysago # zfs rename -r pool/users@2daysago @3daysago # zfs rename -r pool/users@yesterday @2daysago # zfs rename -r pool/users@today @yesterday # zfs snapshot -r pool/users@today
Example 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 -------------------------------------------------------------
Example 23 Showing the differences between a snapshot and a ZFS Dataset
The following example shows how to see what has changed between a prior snapshot of a ZFS Dataset and its current state. The -F option is used to indicate type information for the files affected.
# zfs diff -F tank/test@before tank/test M / /tank/test/ M F /tank/test/linked (+1) R F /tank/test/oldname -> /tank/test/newname - F /tank/test/deleted + F /tank/test/created M F /tank/test/modified
Example 24 Creating a bookmark
The following example create a bookmark to a snapshot. This bookmark can then be used instead of snapshot in send streams.
# zfs bookmark rpool@snapshot rpool#bookmark
ENVIRONMENT VARIABLES
- ZFS_ABORT
- Cause zfs to dump core on exit for the purposes of running ::findleaks.
EXIT STATUS
The following exit values are returned:
0
1
2
SEE ALSO
chmod(2), fsync(2), gzip(1), mount(8), ssh(1), stat(2), write(2), zpool(8)
| November 19, 2013 | ZFS pool 28, filesystem 5 |