Man:zfs
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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 cir-
cumstances. 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" direc-
tory in the root of the file system. Snapshots are automatically
mounted on demand and may be unmounted at regular intervals. The visi-
bility of the ".zfs" directory can be controlled by the "snapdir" prop-
erty.
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 sys-
tems 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" prop-
erty. 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 auto-
matically 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 sys-
tem.
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, mod-
ify, 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 administra-
tor can change properties of the dataset or any of its children. How-
ever, 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. Prop-
erties 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) specifica-
tions:
"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", "snap-
shot", 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 reserva-
tion, 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 cre-
ated, their space is initially shared between the
snapshot and the file system, and possibly with previ-
ous snapshots. As the file system changes, space that
was previously shared becomes unique to the snapshot,
and counted in the snapshot's space used. Addition-
ally, 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 sec-
onds. 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 ini-
tially references the same amount of space as the file
system or snapshot it was created from, since its con-
tents 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 con-
sume. 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 descen-
dants. 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 volblock-
size, and cannot be zero.
The reservation is kept equal to the volume's logical size to pre-
vent 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 pro-
visioning") 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 reserva-
tion 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 reserva-
tion.
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 data-
base can result in significant performance gains. Use of this prop-
erty 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. Other-
wise, 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 sys-
tems 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 automati-
cally 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 per-
mission 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 "dis-
card" 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 inherita-
ble 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 set-
ting 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 sys-
tem. 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 val-
ues 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 distin-
guish them from native properties. They might contain lowercase let-
ters, 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 "mod-
ule: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 sug-
gested 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 Microsys-
tems.
The values of user properties are arbitrary strings, are always inher-
ited, 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 sec-
tion.
Do not swap to a file on a ZFS file system. A ZFS swap file configura-
tion 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 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.
-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 sys-
tems.
-R Recursively destroy all dependents, including cloned file
systems outside the target hierarchy. If a snapshot is speci-
fied, 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 "ori-
gin" 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 snap-
shot 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 snap-
shots 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 snap-
shot 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|/path-
name|./pathname ...
Lists the property information for the given datasets in tabular
form. If specified, you can list property information by the abso-
lute 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 sepa-
rate fields by a single tab instead of arbitrary white-
space.
-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 descend-
ing 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 snap-
shots.
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 "Tem-
porary Mount Point Properties" section for details.
-O Perform an overlay mount. See mount(1M) for more infor-
mation.
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 "Tem-
porary Mount Point Properties" section for details.
-O Perform an overlay mount. See mount(1M) for more infor-
mation.
zfs unmount -a
Unmounts all currently mounted ZFS file systems. Invoked automati-
cally 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 automati-
cally as part of the boot process.
zfs share filesystem
Shares a specific ZFS file system according to the "sharenfs" prop-
erty. 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 snap-
shot2.
The format of the stream is evolving. No backwards compatibility is
guaranteed. You may not be able to receive your streams on future ver-
sions 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 cre-
ated. If the argument is a file system or volume name, a snapshot
with the same name as the sent snapshot is created within the spec-
ified 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 snap-
shot 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 secu-
rity.jail.enforce_statfs should be set to 0 and sysctl secu-
rity.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 snap-
shot 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 con-
tents 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 sys-
tem "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 tar-
get.
# 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 Adminis-
tration Guide: Devices and File Systems.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
1 An error occurred.
2 Invalid command line options were specified.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWzfsu |
+-----------------------------+-----------------------------+
|Interface Stability |Evolving |
+-----------------------------+-----------------------------+
SEE ALSO
gzip(1), ssh(1), mount(1M), share(1M), unshare(1M), zonecfg(1M),
zpool(1M), chmod(2), stat(2), fsync(3c), dfstab(4), attributes(5)
SunOS 5.11 16 Mar 2007 zfs(1M)
