Manual browser: zfs(8)

zfs(1M)

System Administration Commands

zfs(1M)

NAME

zfs - configures ZFS file systems

SYNOPSIS

zfs [-?]

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

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

zfs destroy [-rRf] filesystem|volume|snapshot

zfs clone snapshot filesystem|volume

zfs promote filesystem

zfs rename filesystem|volume|snapshot
[filesystem|volume|snapshot]

zfs snapshot [-r] filesystem@name|volume@name

zfs rollback [-rRf] snapshot

zfs list [-rH] [-o prop[,prop] ]... [ -t type[,type]...]
[ -s prop [-s prop]... [ -S prop [-S prop]...
[filesystem|volume|snapshot|/pathname|./pathname ...

zfs set property=value filesystem|volume ...

zfs get [-rHp] [-o field[,field]...]
[-s source[,source]...] all | property[,property]...
filesystem|volume|snapshot ...

zfs inherit [-r] property filesystem|volume... ...

zfs mount

zfs mount [-o options] [-O] -a

zfs mount [-o options] [-O] filesystem

zfs unmount [-f] -a

zfs unmount [-f] filesystem|mountpoint

zfs share -a

zfs share filesystem

zfs unshare [-f] -a

zfs unshare [-f] filesystem|mountpoint

zfs send [-i snapshot1] snapshot2

zfs receive [-vnF ] filesystem|volume|snapshot

zfs receive [-vnF ] -d filesystem

zfs jail jailid filesystem

zfs unjail jailid filesystem

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 standard POSIX file system. ZFS file systems can be mounted within the standard file system namespace and behave like any other file system.

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. Volumes cannot be used in a non-global zone.

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 will likely 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 zonecfg's "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 zonecfg's "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 zonecfg's "add device" subcommand. However, its physical properties can only be modified 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.

Native Properties

Properties are divided into two types, native properties and user defined 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.

Every dataset has a set of properties that export statistics about the dataset as well as control various behavior. Properties are inherited from the parent unless overridden by the child. Snapshot properties can not be edited; they always inherit their inheritable properties. Properties that are not applicable to snapshots are not displayed.

The values of numeric properties can be specified using the following human-readable suffixes (for example, "k", "KB", "M", "Gb", etc, 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" and "sharenfs".

The first set of properties consist of read-only statistics about the dataset. These properties cannot be set, nor are they inherited. Native properties apply to all dataset types unless otherwise noted.

type

The type of dataset: "filesystem", "volume", "snapshot", or "clone".

creation

The time this dataset was created.

used

The amount of space consumed by this dataset and all its descendants. 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 descendant datasets. The amount of space that a dataset consumes from its parent, as well as the amount of space that will be 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.

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".

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".

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".

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.

The following two properties can be set to control the way space is allocated between datasets. These properties are not inherited, but do affect their descendants.

quota=size | none

Limits the amount of space a dataset and its descendants can consume. This property enforces a hard limit on the amount of space used. This includes all space consumed by descendants, including file systems and snapshots. Setting a quota on a descendant 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.

reservation=size | none

The minimum amount of space guaranteed to a dataset and its descendants. When the amount of space used is below this value, the dataset is treated as if it were taking up the amount of space specified by its reservation. Reservations are accounted for in the parent datasets' space used, and count against the parent datasets' quotas and reservations.

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

volsize=size

For volumes, specifies the logical size of the volume. By default, creating a volume establishes a reservation of equal size. Any changes to volsize are reflected in an equivalent change to the reservation. 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.

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".

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 only affects files created afterward; existing files are unaffected.

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

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.

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.

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. Setting this property on a file system has no direct effect, however.

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, fletcher2, but this may change in future releases). The value "off" disables integrity checking on user data. Disabling checksums is NOT a recommended practice.

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

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".

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".

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".

setuid=on | off

Controls whether the set-UID bit is respected for the file system. The default value is "on".

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".

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".

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".

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 will be made to the ACL other than generating the necessary ACL entries to represent the new mode of the file or directory.

aclinherit=discard | noallow | secure | passthrough

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 "secure" (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.

canmount=on | off

If this property is set to "off", the file system cannot be mounted, and is ignored by "zfs mount -a". This is similar to setting the "mountpoint" property to "none", except that the dataset still has a normal "mountpoint" property which can be inherited. This allows datasets to be used solely as a mechanism to inherit properties. One use case is to have two logically separate datasets have the same mountpoint, so that the children of both datasets appear in the same directory, but may have different inherited characteristics. The default value is " on".

This property is not inherited.

xattr=on | off

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

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=" option.

jailed=on | off

Controls whether the dataset is managed from within a jail. The default value is "off".

iscsioptions

This read-only property, which is hidden, is used by the iSCSI target daemon to store persistent information, such as the IQN. It cannot be viewed or modified using the zfs command. The contents are not intended for external consumers.

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.

User property names must contain a colon (":") character, to distinguish them from native properties. They might 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", etc.) 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.

Volumes as Swap or Dump Devices

To set up a swap area, create a ZFS volume of a specific size and then enable swap on that device. For more information, see the EXAMPLES section.

Do not swap to a file on a ZFS file system. A ZFS swap file configuration is not supported.

Using a ZFS volume as a dump device is not supported.

SUBCOMMANDS

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

zfs ?

Displays a help message.

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

Creates a new ZFS file system. The file system is automatically mounted according to the "mountpoint" property inherited from the parent.

-o property=value

Sets the specified property as if "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 [-s] [-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.

-s

Creates a sparse volume with no reservation. See "volsize" in the Native Properties section for more information about sparse volumes.

-o property=value

-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|snapshot

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, snapshots, clones).

-r

Recursively destroy all children. If a snapshot is specified, destroy all snapshots with this name in descendant file systems.

-R

Recursively destroy all dependents, including cloned file systems outside the target hierarchy. If a snapshot is specified, destroy all snapshots with this name in descendant file systems.

-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 clone 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.

zfs promote 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 snaphot 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

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.

zfs snapshot [-r] filesystem@name|volume@name

Creates a snapshot with the given name. See the "Snapshots" section for details.

-r

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

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 file system is unmounted and remounted, if necessary.

-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

Force an unmount of any file systems using the "unmount -f" command.

zfs list [-rH] [-o prop[,prop] ]... [ -t type[,type]...] [ -s prop [-s prop]... [ -S prop [-S prop]... [filesystem|volume|snapshot|/pathname|./pathname ...

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 datasets are displayed and contain the following fields:

name,used,available,referenced,mountpoint

-H

Used for scripting mode. Do not print headers and separate fields by a single tab instead of arbitrary whitespace.

-r

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

-o prop

A comma-separated list of properties to display. The property must be one of the properties described in the "Native Properties" section, or the special value "name" to display the dataset name.

-s prop

A property to use 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 prop

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" or "volume". For example, specifying "-t snapshot" displays only snapshots.

zfs set property=value filesystem|volume ...

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, Kbytes, Mbytes, gigabytes, terabytes, petabytes, exabytes, or zettabytes, respectively). Properties cannot be set on snapshots.

zfs get [-rHp] [-o field[,field]...] [-s source[,source]...] all | property[,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 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 for the given dataset.

-r

Recursively display properties for any 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

A comma-separated list of columns to display. "name,property,value,source" is the default value.

-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,none". The default value is all sources.

-p

Display numbers in parsable (exact) values.

zfs inherit [-r] property filesystem|volume ...

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.

zfs mount

Displays all ZFS file systems currently mounted.

zfs mount[-o opts] [-O] -a

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

-o opts

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.

zfs mount [-o opts] [-O] filesystem

Mounts a specific ZFS file system. This is typically not necessary, as file systems are automatically mounted when they are created or the mountpoint property has changed. See the "Mount Points" section for details.

-o opts

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.

zfs unmount -a

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

zfs unmount [-f] filesystem|mountpoint

Unmounts the given file system. The command can also be given a path to a ZFS file system mount point on the system.

-f

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

zfs share -a

Shares all available ZFS file systems. This is invoked automatically as part of the boot process.

zfs share filesystem

Shares a specific ZFS file system according to the "sharenfs" property. File systems are shared when the "sharenfs" property is set.

zfs unshare -a

Unshares all currently shared ZFS file systems. This is invoked automatically as part of the shutdown process.

zfs unshare [-F] filesystem|mountpoint

Unshares the given file system. The command can also be given a path to a ZFS file system shared on the system.

-F

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

zfs send [-i snapshot1] snapshot2

Creates a stream representation of snapshot2, 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.

-i snapshot1

Generate an incremental stream from snapshot1 to snapshot2. The incremental source snapshot1 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 snapshot2.

The format of the stream is evolving. No backwards compatibility is guaranteed. You may not be able to receive your streams on future versions of ZFS.

zfs receive [-vnF] filesystem|volume|snapshot

zfs receive [-vnF] -d 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. The destination file system and all of its child file systems are unmounted and cannot be accessed during the receive operation.

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 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 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, any required file systems within the specified one are created.

-d

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

-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 determine what name the receive operation would use.

-F

Force a rollback of the filesystem to the most recent snapshot before performing the receive operation.

zfs jail jailid filesystem

Attaches the given file system to the given jail. From now on this file system tree can be managed from within a jail if the "jailed" property has been set. To use this functionality, sysctl security.jail.enforce_statfs should be set to 0 and sysctl security.jail.mount_allowed should be set to 1.

zfs unjail jailid filesystem

Detaches the given file system from the given jail.

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 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 Taking and destroying multiple snapshots

The following command creates snapshots named "yesterday" of "pool/home" and all of its descendant 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 Turning Off Compression

The following commands turn compression off for all file systems under "pool/home", but explicitly turns it on 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.

# zfs list

NAME USED AVAIL REFER MOUNTPOINT
pool 100G 60G - /pool
pool/home 100G 60G - /export/home
pool/home/bob 40G 60G 40G /export/home/bob
pool/home/bob@yesterday 3M - 40G -
pool/home/anne 60G 60G 40G /export/home/anne

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 Fri Feb 23 14:20 2007 -
pool/home/bob used 24.5K -
pool/home/bob available 50.0G -
pool/home/bob referenced 24.5K -
pool/home/bob compressratio 1.00x -
pool/home/bob mounted yes -
pool/home/bob quota 50G 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 shareiscsi off default
pool/home/bob checksum on default
pool/home/bob compression off default
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 secure default
pool/home/bob canmount on default
pool/home/bob xattr on 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 compression on
pool/home checksum off

Example 8 Rolling Back a ZFS File System

The following command reverts the contents of "pool/home/anne" to the snapshot named "yesterday", deleting all intermediate snapshots.

# zfs rollback -r pool/home/anne@yesterday

Example 9 Creating a ZFS Clone

The following command creates a writable file system whose initial contents are the same as "pool/home/bob@yesterday".

# zfs clone pool/home/bob@yesterday pool/clone

Example 10 Promoting a ZFS Clone

The following commands illustrate how to test out changes to a file system, and then replace the original file system with the changed one, using clones, clone promotion, and renaming:

# zfs create pool/project/production
populate /pool/project/production with data
# zfs snapshot pool/project/production@today
# zfs clone pool/project/production@today pool/project/beta
make changes to /pool/project/beta and test them
# zfs promote pool/project/beta
# zfs rename pool/project/production pool/project/legacy
# zfs rename pool/project/beta pool/project/production
once the legacy version is no longer needed, it can be
destroyed
# zfs destroy pool/project/legacy

Example 11 Inheriting ZFS Properties

The following command causes "pool/home/bob" and "pool/home/anne" to inherit the "checksum" property from their parent.

# zfs inherit checksum pool/home/bob pool/home/anne

Example 12 Remotely Replicating ZFS Data

The following commands send a full stream and then an incremental stream to a remote machine, restoring them into "poolB/received/fs@a" and "poolB/received/fs@b", respectively. "poolB" must contain the file system " poolB/received", and must not initially contain "poolB/received/fs".

# zfs send pool/fs@a | \
ssh host zfs receive poolB/received/fs@a
# zfs send -i a pool/fs@b | ssh host \
zfs receive poolB/received/fs

Example 13 Using the zfs receive -d Option

The following command sends a full stream of "poolA/fsA/fsB@snap" to a remote machine, receiving it into "poolB/received/fsA/fsB@snap". The "fsA/fsB@snap" portion of the received snapshot's name is determined from the name of the sent snapshot. " poolB" must contain the file system "poolB/received". If "poolB/received/fsA" does not exist, it will be created as an empty file system.

# zfs send poolA/fsA/fsB@snap | \
ssh host zfs receive -d poolB/received

Example 14 Creating a ZFS volume as a Swap Device

The following example shows how to create a 5-Gbyte ZFS volume and then add the volume as a swap device.

# zfs create -V 5gb tank/vol
# swap -a /dev/zvol/dsk/tank/vol

Example 15 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 16 Creating a ZFS Volume as a 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 the Solaris Administration Guide: Devices and File Systems.

EXIT STATUS

The following exit values are returned:

Successful completion.

An error occurred.

Invalid command line options were specified.

ATTRIBUTES

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