NAME
zpool - configures ZFS storage pools
SYNOPSIS
zpool [-?]
zpool create [-fn] [-R root] [-m mountpoint] pool vdev ...
zpool destroy [-f] pool
zpool add [-fn] pool vdev
zpool remove pool vdev
zpool list [-H] [-o field[,field]*] [pool] ...
zpool iostat [-v] [pool] ... [interval [count]]
zpool status [-xv] [pool] ...
zpool offline [-t] pool device ...
zpool online pool device ...
zpool clear pool [device] ...
zpool attach [-f] pool device new_device
zpool detach pool device
zpool replace [-f] pool device [new_device]
zpool scrub [-s] pool ...
zpool export [-f] pool
zpool import [-d dir] [-D]
zpool import [-d dir] [-D] [-f] [-o opts] [-R root] pool | id
[ newpool]
zpool import [-d dir] [-D] [-f] [-a]
zpool upgrade
zpool upgrade -v
zpool upgrade [-a | pool]
zpool history [pool] ...
DESCRIPTION
The
zpool command configures
ZFS storage pools. A storage pool is
a collection of devices that provides physical storage and data replication
for
ZFS datasets.
All datasets within a storage pool share the same space. See
zfs(1M) for
information on managing datasets.
Virtual Devices (vdevs)
A "virtual device" describes a single device or a collection of
devices organized according to certain performance and fault characteristics.
The following virtual devices are supported:
disk
A block device, typically located under
"/dev/dsk". ZFS can use individual slices or partitions,
though the recommended mode of operation is to use whole disks. A disk can be
specified by a full path, or it can be a shorthand name (the relative portion
of the path under "/dev/dsk"). A whole disk can be specified by
omitting the slice or partition designation. For example, "c0t0d0"
is equivalent to "/dev/dsk/c0t0d0s2". When given a whole disk,
ZFS automatically labels the disk, if necessary.
file
A regular file. The use of files as a backing
store is strongly discouraged. It is designed primarily for experimental
purposes, as the fault tolerance of a file is only as good as the file system
of which it is a part. A file must be specified by a full path.
mirror
A mirror of two or more devices. Data is
replicated in an identical fashion across all components of a mirror. A mirror
with N disks of size X can hold X bytes and can withstand
( N-1) devices failing before data integrity is compromised.
raidz
raidz1
raidz2
A variation on
RAID-5 that allows for
better distribution of parity and eliminates the "
RAID-5 write
hole" (in which data and parity become inconsistent after a power loss).
Data and parity is striped across all disks within a
raidz group.
A
raidz group can have either single- or double-parity, meaning that the
raidz group can sustain one or two failures respectively without losing
any data. The
raidz1 vdev type specifies a single-parity
raidz group and the
raidz2 vdev type specifies a
double-parity
raidz group. The
raidz vdev type is an
alias for
raidz1.
A
raidz group with
N disks of size
X with
P parity
disks can hold approximately (
N-P)*
X bytes and can withstand
one device failing before data integrity is compromised. The minimum number of
devices in a
raidz group is one more than the number of parity disks.
The recommended number is between 3 and 9.
spare
A special pseudo-vdev which keeps
track of available hot spares for a pool. For more information, see the
"Hot Spares" section.
Virtual devices cannot be nested, so a mirror or
raidz virtual device can
only contain files or disks. Mirrors of mirrors (or other combinations) are
not allowed.
A pool can have any number of virtual devices at the top of the configuration
(known as "root vdevs"). Data is dynamically distributed across all
top-level devices to balance data among devices. As new virtual devices are
added,
ZFS automatically places data on the newly available devices.
Virtual devices are specified one at a time on the command line, separated by
whitespace. The keywords "mirror" and "raidz" are used to
distinguish where a group ends and another begins. For example, the following
creates two root vdevs, each a mirror of two disks:
# zpool create mypool mirror c0t0d0 c0t1d0 mirror c1t0d0 c1t1d0
Device Failure and Recovery
ZFS supports a rich set of mechanisms for handling device failure and
data corruption. All metadata and data is checksummed, and
ZFS
automatically repairs bad data from a good copy when corruption is detected.
In order to take advantage of these features, a pool must make use of some form
of redundancy, using either mirrored or
raidz groups. While
ZFS
supports running in a non-redundant configuration, where each root vdev is
simply a disk or file, this is strongly discouraged. A single case of bit
corruption can render some or all of your data unavailable.
A pool's health status is described by one of three states: online, degraded, or
faulted. An online pool has all devices operating normally. A degraded pool is
one in which one or more devices have failed, but the data is still available
due to a redundant configuration. A faulted pool has one or more failed
devices, and there is insufficient redundancy to replicate the missing data.
Hot Spares
ZFS allows devices to be associated with pools as "hot spares".
These devices are not actively used in the pool, but when an active device
fails, it is automatically replaced by a hot spare. To create a pool with hot
spares, specify a "spare"
vdev with any number of devices.
For example,
# zpool create pool mirror c0d0 c1d0 spare c2d0 c3d0
Spares can be shared across multiple pools, and can be added with the
"zpool add" command and removed with the "zpool remove"
command. Once a spare replacement is initiated, a new "spare"
vdev is created within the configuration that will remain there until
the original device is replaced. At this point, the hot spare becomes
available again if another device fails.
An in-progress spare replacement can be cancelled by detaching the hot spare. If
the original faulted device is detached, then the hot spare assumes its place
in the configuration, and is removed from the spare list of all active pools.
Alternate Root Pools
The "zpool create -R" and "zpool import -R" commands allow
users to create and import a pool with a different root path. By default,
whenever a pool is created or imported on a system, it is permanently added so
that it is available whenever the system boots. For removable media, or when
in recovery situations, this may not always be desirable. An alternate root
pool does not persist on the system. Instead, it exists only until exported or
the system is rebooted, at which point it will have to be imported again.
In addition, all mount points in the pool are prefixed with the given root, so a
pool can be constrained to a particular area of the file system. This is most
useful when importing unknown pools from removable media, as the mount points
of any file systems cannot be trusted.
When creating an alternate root pool, the default mount point is "/",
rather than the normal default "/
pool".
Subcommands
All subcommands that modify state are logged persistently to the pool in their
original form.
The
zpool command provides subcommands to create and destroy storage
pools, add capacity to storage pools, and provide information about the
storage pools. The following subcommands are supported:
zpool -?
Displays a help message.
zpool create [
-fn] [
-R root] [
-m
mountpoint]
pool vdev ...
Creates a new storage pool containing the
virtual devices specified on the command line. The pool name must begin with a
letter, and can only contain alphanumeric characters as well as underscore
("_"), dash ("-"), and period ("."). The pool
names "mirror", "raidz", and "spare" are
reserved, as are names beginning with the pattern "c[0-9]". The
vdev specification is described in the "Virtual Devices"
section.
The command verifies that each device specified is accessible and not currently
in use by another subsystem. There are some uses, such as being currently
mounted, or specified as the dedicated dump device, that prevents a device
from ever being used by
ZFS. Other uses, such as having a preexisting
UFS file system, can be overridden with the
-f option.
The command also checks that the replication strategy for the pool is
consistent. An attempt to combine redundant and non-redundant storage in a
single pool, or to mix disks and files, results in an error unless
-f
is specified. The use of differently sized devices within a single
raidz or mirror group is also flagged as an error unless
-f is
specified.
Unless the
-R option is specified, the default mount point is
"/
pool". The mount point must not exist or must be empty, or
else the root dataset cannot be mounted. This can be overridden with the
-m option.
-f
Forces use of vdevs, even if they
appear in use or specify a conflicting replication level. Not all devices can
be overridden in this manner.
-n
Displays the configuration that would be used
without actually creating the pool. The actual pool creation can still fail
due to insufficient privileges or device sharing.
-R root
Creates the pool with an alternate
root. See the "Alternate Root Pools" section. The root
dataset has its mount point set to "/" as part of this
operation.
-m mountpoint
Sets the mount point for the root dataset.
The default mount point is "/ pool". The mount point must be
an absolute path, " legacy", or "none". For
more information on dataset mount points, see zfs(1M).
zpool destroy [
-f]
pool
Destroys the given pool, freeing up any
devices for other use. This command tries to unmount any active datasets
before destroying the pool.
-f
Forces any active datasets contained within
the pool to be unmounted.
zpool add [
-fn]
pool vdev ...
Adds the specified virtual devices to the
given pool. The
vdev specification is described in the "Virtual
Devices" section. The behavior of the
-f option, and the device
checks performed are described in the "zpool create" subcommand.
-f
Forces use of vdevs, even if they
appear in use or specify a conflicting replication level. Not all devices can
be overridden in this manner.
-n
Displays the configuration that would be used
without actually adding the vdevs. The actual pool creation can still
fail due to insufficient privileges or device sharing.
Do not add a disk that is currently configured as a quorum device to a zpool.
Once a disk is in a zpool, that disk can then be configured as a quorum
device.
zpool remove pool vdev
Removes the given vdev from the pool.
This command currently only supports removing hot spares. Devices which are
part of a mirror can be removed using the "zpool detach" command.
Raidz and top-level vdevs cannot be removed from a pool.
zpool list [
-H] [
-o field[,
field*]]
[
pool] ...
Lists the given pools along with a health
status and space usage. When given no arguments, all pools in the system are
listed.
-H
Scripted mode. Do not display headers, and
separate fields by a single tab instead of arbitrary space.
-o field
Comma-separated list of fields to display.
Each field must be one of:
name Pool name
size Total size
used Amount of space used
available Amount of space available
capacity Percentage of pool space used
health Health status
The default is all fields.
This command reports actual physical space available to the storage pool. The
physical space can be different from the total amount of space that any
contained datasets can actually use. The amount of space used in a
raidz configuration depends on the characteristics of the data being
written. In addition,
ZFS reserves some space for internal accounting
that the
zfs(1M) command takes into account, but the
zpool
command does not. For non-full pools of a reasonable size, these effects
should be invisible. For small pools, or pools that are close to being
completely full, these discrepancies may become more noticeable.
zpool iostat [
-v] [
pool] ... [
interval
[
count]]
Displays
I/O statistics for the given
pools. When given an interval, the statistics are printed every
interval seconds until
Ctrl-C is pressed. If no
pools are
specified, statistics for every pool in the system is shown. If
count
is specified, the command exits after
count reports are printed.
-v
Verbose statistics. Reports usage statistics
for individual vdevs within the pool, in addition to the pool-wide
statistics.
zpool status [
-xv] [
pool] ...
Displays the detailed health status for the
given pools. If no
pool is specified, then the status of each pool in
the system is displayed.
If a scrub or resilver is in progress, this command reports the percentage done
and the estimated time to completion. Both of these are only approximate,
because the amount of data in the pool and the other workloads on the system
can change.
-x
Only display status for pools that are
exhibiting errors or are otherwise unavailable.
-v
Displays verbose data error information,
printing out a complete list of all data errors since the last complete pool
scrub.
zpool offline [
-t]
pool device ...
Takes the specified physical device offline.
While the
device is offline, no attempt is made to read or write to the
device.
This command is not applicable to spares.
-t
Temporary. Upon reboot, the specified physical
device reverts to its previous state.
zpool online pool device ...
Brings the specified physical device online.
This command is not applicable to spares.
zpool clear pool [
device] ...
Clears device errors in a pool. If no
arguments are specified, all device errors within the pool are cleared. If one
or more devices is specified, only those errors associated with the specified
device or devices are cleared.
zpool attach [
-f]
pool device
new_device
Attaches
new_device to an existing
zpool device. The existing device cannot be part of a
raidz
configuration. If
device is not currently part of a mirrored
configuration,
device automatically transforms into a two-way mirror of
device and
new_device. If
device is part of a two-way
mirror, attaching
new_device creates a three-way mirror, and so on. In
either case,
new_device begins to resilver immediately.
-f
Forces use of new_device, even if its
appears to be in use. Not all devices can be overridden in this manner.
zpool detach pool device
Detaches device from a mirror. The
operation is refused if there are no other valid replicas of the data.
zpool replace [
-f]
pool old_device
[
new_device]
Replaces
old_device with
new_device. This is equivalent to attaching
new_device, waiting
for it to resilver, and then detaching
old_device.
The size of
new_device must be greater than or equal to the minimum size
of all the devices in a mirror or
raidz configuration.
If
new_device is not specified, it defaults to
old_device. This
form of replacement is useful after an existing disk has failed and has been
physically replaced. In this case, the new disk may have the same
/dev/dsk path as the old device, even though it is actually a different
disk.
ZFS recognizes this.
-f
Forces use of new_device, even if its
appears to be in use. Not all devices can be overridden in this manner.
zpool scrub [
-s]
pool ...
Begins a scrub. The scrub examines all data in
the specified pools to verify that it checksums correctly. For replicated
(mirror or
raidz) devices,
ZFS automatically repairs any damage
discovered during the scrub. The "
zpool status"
command reports the progress of the scrub and summarizes the results of the
scrub upon completion.
Scrubbing and resilvering are very similar operations. The difference is that
resilvering only examines data that
ZFS knows to be out of date (for
example, when attaching a new device to a mirror or replacing an existing
device), whereas scrubbing examines all data to discover silent errors due to
hardware faults or disk failure.
Because scrubbing and resilvering are
I/O-intensive operations,
ZFS only allows one at a time. If a scrub is already in progress, the
"
zpool scrub" command terminates it and starts a new scrub.
If a resilver is in progress,
ZFS does not allow a scrub to be started
until the resilver completes.
-s
Stop scrubbing.
zpool export [
-f]
pool ...
Exports the given pools from the system. All
devices are marked as exported, but are still considered in use by other
subsystems. The devices can be moved between systems (even those of different
endianness) and imported as long as a sufficient number of devices are
present.
Before exporting the pool, all datasets within the pool are unmounted.
For pools to be portable, you must give the
zpool command whole disks,
not just slices, so that
ZFS can label the disks with portable
EFI labels. Otherwise, disk drivers on platforms of different
endianness will not recognize the disks.
-f
Forcefully unmount all datasets, using the
" unmount -f" command.
zpool import [
-d dir] [
-D]
Lists pools available to import. If the
-d option is not specified, this command searches for devices in
"/dev/dsk". The
-d option can be specified multiple times,
and all directories are searched. If the device appears to be part of an
exported pool, this command displays a summary of the pool with the name of
the pool, a numeric identifier, as well as the
vdev layout and current
health of the device for each device or file. Destroyed pools, pools that were
previously destroyed with the "
-zpool destroy" command, are
not listed unless the
-D option is specified.
The numeric identifier is unique, and can be used instead of the pool name when
multiple exported pools of the same name are available.
-d dir
Searches for devices or files in dir.
The -d option can be specified multiple times.
-D
Lists destroyed pools only.
zpool import [
-d dir] [
-D] [
-f]
[
-o opts] [
-R root]
pool |
id
[
newpool]
Imports a specific pool. A pool can be
identified by its name or the numeric identifier. If
newpool is
specified, the pool is imported using the name
newpool. Otherwise, it
is imported with the same name as its exported name.
If a device is removed from a system without running "
zpool
export" first, the device appears as potentially active. It cannot be
determined if this was a failed export, or whether the device is really in use
from another host. To import a pool in this state, the
-f option is
required.
-d dir
Searches for devices or files in dir.
The -d option can be specified multiple times.
-D
Imports destroyed pool. The -f option
is also required.
-f
Forces import, even if the pool appears to be
potentially active.
-o opts
Comma-separated list of mount options to use
when mounting datasets within the pool. See zfs(1M) for a description
of dataset properties and mount options.
-R root
Imports pool(s) with an alternate
root. See the "Alternate Root Pools" section.
zpool import [
-d dir] [
-D] [
-f]
[
-a]
Imports all pools found in the search
directories. Identical to the previous command, except that all pools with a
sufficient number of devices available are imported. Destroyed pools, pools
that were previously destroyed with the "
-zpool destroy"
command, will not be imported unless the
-D option is specified.
-d dir
Searches for devices or files in dir.
The -d option can be specified multiple times.
-D
Imports destroyed pools only. The -f
option is also required.
-f
Forces import, even if the pool appears to be
potentially active.
zpool upgrade
Displays all pools formatted using a different
ZFS on-disk version. Older versions can continue to be used, but some
features may not be available. These pools can be upgraded using "
zpool upgrade -a". Pools that are formatted with a more recent
version are also displayed, although these pools will be inaccessible on the
system.
zpool upgrade -v
Displays ZFS versions supported by the
current software. The current ZFS versions and all previous
supportedversions are displayed, along with an explanation of the features
provided with each version.
zpool upgrade [
-a |
pool]
Upgrades the given pool to the latest on-disk
version. Once this is done, the pool will no longer be accessible on systems
running older versions of the software.
-a
Upgrades all pools.
zpool history [
pool] ...
Displays the command history of the specified
pools (or all pools if no pool is specified).
EXAMPLES
Example 1 Creating a RAID-Z Storage Pool
The following command creates a pool with a single
raidz root
vdev
that consists of six disks.
# zpool create tank raidz c0t0d0 c0t1d0 c0t2d0 c0t3d0 c0t4d0 c0t5d0
Example 2 Creating a Mirrored Storage Pool
The following command creates a pool with two mirrors, where each mirror
contains two disks.
# zpool create tank mirror c0t0d0 c0t1d0 mirror c0t2d0 c0t3d0
Example 3 Creating a ZFS Storage Pool by Using Slices
The following command creates an unmirrored pool using two disk slices.
# zpool create tank /dev/dsk/c0t0d0s1 c0t1d0s4
Example 4 Creating a ZFS Storage Pool by Using Files
The following command creates an unmirrored pool using files. While not
recommended, a pool based on files can be useful for experimental purposes.
# zpool create tank /path/to/file/a /path/to/file/b
Example 5 Adding a Mirror to a ZFS Storage Pool
The following command adds two mirrored disks to the pool "
tank", assuming the pool is already made up of two-way mirrors.
The additional space is immediately available to any datasets within the pool.
# zpool add tank mirror c1t0d0 c1t1d0
Example 6 Listing Available ZFS Storage Pools
The following command lists all available pools on the system. In this case, the
pool
zion is faulted due to a missing device.
The results from this command are similar to the following:
# zpool list
NAME SIZE USED AVAIL CAP HEALTH ALTROOT
pool 67.5G 2.92M 67.5G 0% ONLINE -
tank 67.5G 2.92M 67.5G 0% ONLINE -
zion - - - 0% FAULTED -
Example 7 Destroying a ZFS Storage Pool
The following command destroys the pool "
tank" and any
datasets contained within.
# zpool destroy -f tank
Example 8 Exporting a ZFS Storage Pool
The following command exports the devices in pool
tank so that they can
be relocated or later imported.
# zpool export tank
Example 9 Importing a ZFS Storage Pool
The following command displays available pools, and then imports the pool
"tank" for use on the system.
The results from this command are similar to the following:
# zpool import
pool: tank
id: 15451357997522795478
state: ONLINE
action: The pool can be imported using its name or numeric identifier.
config:
tank ONLINE
mirror ONLINE
c1t2d0 ONLINE
c1t3d0 ONLINE
# zpool import tank
Example 10 Upgrading All ZFS Storage Pools to the Current Version
The following command upgrades all ZFS Storage pools to the current version of
the software.
# zpool upgrade -a
This system is currently running ZFS version 2.
Example 11 Managing Hot Spares
The following command creates a new pool with an available hot spare:
# zpool create tank mirror c0t0d0 c0t1d0 spare c0t2d0
If one of the disks were to fail, the pool would be reduced to the degraded
state. The failed device can be replaced using the following command:
# zpool replace tank c0t0d0 c0t3d0
Once the data has been resilvered, the spare is automatically removed and is
made available should another device fails. The hot spare can be permanently
removed from the pool using the following command:
# zpool remove tank c0t2d0
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
zfs(1M),
attributes(5)