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# man zfs
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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
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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 -a
zfs unshare filesystem|mountpoint
zfs send [-i snapshot1] snapshot2
zfs receive [-vnF ] filesystem|volume|snapshot
zfs receive [-vnF ] -d 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 sys-
tems can be mounted within the standard file
system namespace and behave like any other
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file system.
volume A logical volume exported as a block device.
This type of dataset should only be used
under special circumstances; file systems are
typically used. 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 speci-
fied 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,
including 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 adminis-
tering 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
that 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 indepen-
dently.
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,
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creating a clone is nearly instantaneous, and initially con-
sumes 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" pro-
perty 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
Because creating a ZFS file system is a simple operation,
the number of file systems per system will likely be much
greater. To cope with this, ZFS automatically manages mount-
ing 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. Direc-
tories 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 tradi-
tional 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.
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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 con-
trolled 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 global administrator.
A ZFS emulated volume can be added as a device to a non-
global zone by using zonecfg's "add device" subcommand. How-
ever, its physical properties can only be modified by the
global administrator.
For more information about zonecfg syntax, see zonecfg(1M).
Once 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 set the mount point to an unaccept-
able value.
The global administrator can forcibly clear the "zoned" pro-
perty, 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 on user properties,
see the "User Properties" section.
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Every dataset has a set of properties that export statistics
about the dataset as well as control various behavior. Pro-
perties 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 reser-
vation, 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" sec-
tion) are created, their space is initially
shared between the snapshot and the file
system, and possibly with previous
snapshots. As the file system changes,
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space that was previously shared becomes
unique to the snapshot, and counted in the
snapshot's space used. Additionally, delet-
ing 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 pend-
ing changes. Pending changes are generally
accounted for within a few seconds. Commit-
ting 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 ident-
ical.
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
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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 descendents.
quota=size | none
Limits the amount of space a dataset and its descendents
can consume. This property enforces a hard limit on the
amount of space used. This includes all space consumed
by descendents, including file systems and snapshots.
Setting a quota on a descendent of a dataset that
already has a quota does not override the ancestor's
quota, but rather imposes an additional limit.
Quotas cannot be set on volumes, as the "volsize" pro-
perty acts as an implicit quota.
reservation=size | none
The minimum amount of space guaranteed to a dataset and
its descendents. When the amount of space used is below
this value, the dataset is treated as if it were taking
up the amount of space specified by its reservation.
Reservations are accounted for in the parent datasets'
space used, and count against the parent datasets' quo-
tas 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
for the same amount. Any changes to volsize are
reflected in an equivalent change to the reservation.
The volsize can only be set to a multiple of volblock-
size, and cannot be zero.
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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 corrup-
tion, 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 pat-
terns.
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.
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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 is used.
When the mountpoint property is changed for a file sys-
tem, 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 automat-
ically 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 loca-
tion.
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). Other-
wise, the file system is automatically shared and
unshared with the "zfs share" and "zfs unshare" com-
mands. 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 pro-
perty 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
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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 sys-
tem 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
Controls the compression algorithm used for this
dataset. There is currently only one algorithm, "lzjb",
though this may change in future releases. The default
value is "off".
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 may
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".
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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 informa-
tion. The default value is "off".
snapdir=hidden | visible
Controls whether the ".zfs" directory is hidden or visi-
ble 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 gen-
erating 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
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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 inher-
ited. 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 dif-
ferent 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".
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 com-
mand. 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 proper-
ties. 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
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xattr xattr/noxattr
In addition, these options can be set on a per-mount basis
using the -o option, without affecting the propertyS that is
stored on disk. The values specified on the command line
will override the values stored in the dataset. The -nosuid
option is an alias for "nodevices,nosetuid". These proper-
ties 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 may contain
lowercase letters, numbers, and the following punctuation
characters: colon (":"), dash ("-"), period ("."), and
underscore ("_"). The expected convention is that the pro-
perty 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 will use the same pro-
perty 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 com-
mands which operate on properties ("zfs list", "zfs get",
"zfs set", etc.) can be used to manipulate both native pro-
perties and user properties. Use the "zfs inherit" command
to clear a user property . If the property is not defined in
any parent dataset, it will be 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
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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 will
automatically be 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 will
result 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
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Native Properties section for more
information about sparse volumes.
-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 will
result if the same property is
specified in multiple -o options.
-b blocksize Equivalent to "-o
volblocksize=blocksize". If this
option is specified in conjunction
with "-o volblocksize", the result-
ing 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 depen-
dents (children, snapshots, clones).
-r Recursively destroy all children. If a snapshot is
specified, destroy all snapshots with this name in
descendent 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 descendent 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.
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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 des-
troy 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, will now be owned by the promoted
clone. The space they use will move from the "origin"
file system to the promoted clone, so there must have
enough space 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 conflict-
ing 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.
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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 inter-
mediate 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 infor-
mation by the absolute pathname or the relative path-
name. 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 pro-
perties described in the "Native Properties"
section, or the special value "name" to
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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 order-
ing.
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, specify-
ing "-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 speci-
fied 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
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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 pro-
perties for all datasets on the system. For each pro-
perty, 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 pro-
perties 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.
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-p Display numbers in parsable (exact) values.
zfs inherit [-r] property filesystem|volume ...
Clears the specified property, causing it to be inher-
ited from an ancestor. If no ancestor has the property
set, then the default value is used. See the "Proper-
ties" 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 automati-
cally 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.
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-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 filesystem|mountpoint
Unshares the given file system. The command can also be
given a path to a ZFS file system shared on the system.
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 machine (for example, using
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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
will be assumed to be from the same file
system as snapshot2.
The format of the stream is evolving. No backwards compati-
bility 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 destina-
tion 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 sys-
tems 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 speci-
fied, 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 para-
graph above.
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-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 deter-
mine what name the receive operation would use.
-F Force a rollback of the filesystem to the most
recent snapshot before performing the receive
operation.
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 sys-
tem, 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 descendent file systems. Each
snapshot is mounted on demand in the ".zfs/snapshot" direc-
tory at the root of its file system. The second command des-
troys the newly created snapshots.
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# 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
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The following command lists all properties for
"pool/home/bob".
# zfs get -o property,value,source all pool/home/bob
PROPERTY VALUE SOURCE
type filesystem -
creation Tue Feb 14 15:51 2006 -
used 571K -
available 50.0G -
referenced 376K -
compressratio 1.00x -
mounted yes -
quota 50G local
reservation none default
recordsize 128K default
mountpoint /pool/home/bob default
sharenfs off default
shareiscsi off default
checksum on default
compression on local
atime on default
devices on default
exec on default
setuid on default
readonly off default
zoned off default
snapdir visible default
aclmode groupmask default
aclinherit secure default
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 set-
tings for "pool/home/bob".
# zfs get -r -s local -o name,property,value all pool/home/bob
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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
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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 incre-
mental stream to a remote machine, restoring them into
"poolB/received/fs@a" and "poolB/received/fs@b", respec-
tively. "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
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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 initia-
tor. For more information about the Solaris iSCSI initiator,
see the Solaris Administration Guide: Devices and File Sys-
tems.
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 sys-
tem.
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# 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.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
1 An error occurred.
2 Invalid command line options were specified.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWzfsu |
|_____________________________|_____________________________|
| Interface Stability | Evolving |
|_____________________________|_____________________________|
SEE ALSO
ssh(1), mount(1M), share(1M), unshare(1M), zonecfg(1M),
zpool(1M), chmod(2), stat(2), fsync(3c), dfstab(4), attri-
butes(5)
For information about using the ZFS web-based management
tool and other ZFS features, see the ZFS Administration
Guide.
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