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ZPOOL(8) System Manager's Manual ZPOOL(8) NAME zpool -- configures ZFS storage pools SYNOPSIS zpool [-?] zpool add [-fn] pool vdev ... zpool attach [-f] pool device new_device zpool clear [-F [-n]] pool [device] zpool create [-fnd] [-o property=value] ... [-O file-system-property=value] ... [-m mountpoint] [-R root] pool vdev ... zpool destroy [-f] pool zpool detach pool device zpool export [-f] pool ... zpool get all | property[,...] pool ... zpool history [-il] [pool] ... zpool import [-d dir | -c cachefile] [-D] zpool import [-o mntopts] [-o property=value] ... [-d dir | -c cachefile] [-D] [-f] [-m] [-N] [-R root] [-F [-n]] -a zpool import [-o mntopts] [-o property=value] ... [-d dir | -c cachefile] [-D] [-f] [-m] [-N] [-R root] [-F [-n]] pool | id [newpool] zpool iostat [-T d|u] [-v] [pool] ... zpool labelclear [-f] device zpool list [-H] [-o property[,...]] [-T d|u] [pool] ... [inverval [count]] zpool offline [-t] pool device ... zpool online [-e] pool device ... zpool reguid pool zpool remove pool device ... zpool replace [-f] pool device [new_device] zpool scrub [-s] pool ... zpool set property=value pool zpool split [-n] [-R altroot] [-o mntopts] [-o property=value] pool newpool [device ...] zpool status [-vx] [-T d|u] [pool] ... [interval [count]] zpool upgrade [-v] zpool upgrade [-V version] -a | pool ... DESCRIPTION The zpool command configures ZFS storage pools. A storage pool is a collection of devices that provides physical storage and data replica- tion for ZFS datasets. All datasets within a storage pool share the same space. See zfs(8) for information on managing datasets. Virtual Devices (vdevs) A "virtual device" (vdev) describes a single device or a collection of devices organized according to certain performance and fault character- istics. The following virtual devices are supported: disk A block device, typically located under /dev. ZFS can use in- dividual slices or partitions, though the recommended mode of operation is to use whole disks. A disk can be specified by a full path to the device or the geom(4) provider name. When given a whole disk, ZFS automatically labels the disk, if nec- essary. file A regular file. The use of files as a backing store is strongly discouraged. It is designed primarily for experimental pur- poses, as the fault tolerance of a file is only as good 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 iden- tical fashion across all components of a mirror. A mirror with N disks of size X can hold X bytes and can withstand (N-1) de- vices failing before data integrity is compromised. raidz (or raidz1 raidz2 raidz3). 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 single-, double- , or triple parity, meaning that the raidz group can sustain one, two, or three failures, respectively, without losing any data. The raidz1 vdev type specifies a single-parity raidz group; the raidz2 vdev type specifies a double-parity raidz group; and the raidz3 vdev type specifies a triple-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 P device(s) failing before data integrity is compromised. The minimum num- ber of devices in a raidz group is one more than the number of parity disks. The recommended number is between 3 and 9 to help increase performance. spare A special pseudo-vdev which keeps track of available hot spares for a pool. For more information, see the ""Hot Spares"" sec- tion. log A separate-intent log device. If more than one log device is specified, then writes are load-balanced between devices. Log devices can be mirrored. However, raidz vdev types are not sup- ported for the intent log. For more information, see the ""Intent Log"" section. cache A device used to cache storage pool data. A cache device cannot be configured as a mirror or raidz group. For more information, see the ""Cache Devices"" section. Virtual devices cannot be nested, so a mirror or raidz virtual device can only contain files or disks. Mirrors of mirrors (or other combina- tions) are not allowed. A pool can have any number of virtual devices at the top of the config- uration (known as "root" vdevs). Data is dynamically distributed across all top-level devices to balance data among devices. As new virtual de- vices are added, ZFS automatically places data on the newly available devices. Virtual devices are specified one at a time on the command line, sepa- rated by whitespace. The keywords "mirror" and "raidz" are used to dis- tinguish where a group ends and another begins. For example, the fol- lowing creates two root vdevs, each a mirror of two disks: # zpool create mypool mirror da0 da1 mirror da2 da3 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 automat- ically 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, de- graded, 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 corrupted metadata, or one or more faulted devices, and insuf- ficient replicas to continue functioning. The health of the top-level vdev, such as mirror or raidz device, is potentially impacted by the state of its associated vdevs, or component devices. A top-level vdev or component device is in one of the follow- ing states: DEGRADED One or more top-level vdevs is in the degraded state because one or more component devices are offline. Sufficient repli- cas exist to continue functioning. One or more component devices is in the degraded or faulted state, but sufficient replicas exist to continue functioning. The underlying conditions are as follows: o The number of checksum errors exceeds acceptable levels and the device is degraded as an indication that some- thing may be wrong. ZFS continues to use the device as necessary. o The number of I/O errors exceeds acceptable levels. The device could not be marked as faulted because there are insufficient replicas to continue functioning. FAULTED One or more top-level vdevs is in the faulted state because one or more component devices are offline. Insufficient replicas exist to continue functioning. One or more component devices is in the faulted state, and insufficient replicas exist to continue functioning. The un- derlying conditions are as follows: o The device could be opened, but the contents did not match expected values. o The number of I/O errors exceeds acceptable levels and the device is faulted to prevent further use of the de- vice. OFFLINE The device was explicitly taken offline by the "zpool offline" command. ONLINE The device is online and functioning. REMOVED The device was physically removed while the system was run- ning. Device removal detection is hardware-dependent and may not be supported on all platforms. UNAVAIL The device could not be opened. If a pool is imported when a device was unavailable, then the device will be identified by a unique identifier instead of its path since the path was never correct in the first place. If a device is removed and later reattached to the system, ZFS attempts to put the device online automatically. Device attach detection is hardware-dependent and might not be supported on all platforms. 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 da0 da1 spare da2 da3 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 an- other device fails. If a pool has a shared spare that is currently being used, the pool can not be exported since other pools may use this shared spare, which may lead to potential data corruption. 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. Spares cannot replace log devices. Intent Log The ZFS Intent Log (ZIL) satisfies POSIX requirements for synchronous transactions. For instance, databases often require their transactions to be on stable storage devices when returning from a system call. NFS and other applications can also use fsync(2) to ensure data stability. By default, the intent log is allocated from blocks within the main pool. However, it might be possible to get better performance using separate intent log devices such as NVRAM or a dedicated disk. For ex- ample: # zpool create pool da0 da1 log da2 Multiple log devices can also be specified, and they can be mirrored. See the "EXAMPLES" section for an example of mirroring multiple log de- vices. Log devices can be added, replaced, attached, detached, imported and exported as part of the larger pool. Mirrored log devices can be re- moved by specifying the top-level mirror for the log. Cache devices Devices can be added to a storage pool as "cache devices." These de- vices provide an additional layer of caching between main memory and disk. For read-heavy workloads, where the working set size is much larger than what can be cached in main memory, using cache devices al- low much more of this working set to be served from low latency media. Using cache devices provides the greatest performance improvement for random read-workloads of mostly static content. To create a pool with cache devices, specify a "cache" vdev with any number of devices. For example: # zpool create pool da0 da1 cache da2 da3 Cache devices cannot be mirrored or part of a raidz configuration. If a read error is encountered on a cache device, that read I/O is reissued to the original storage pool device, which might be part of a mirrored or raidz configuration. The content of the cache devices is considered volatile, as is the case with other system caches. Properties Each pool has several properties associated with it. Some properties are read-only statistics while others are configurable and change the behavior of the pool. The following are read-only properties: alloc Amount of storage space within the pool that has been phys- ically allocated. capacity Percentage of pool space used. This property can also be referred to by its shortened column name, "cap". comment A text string consisting of printable ASCII characters that will be stored such that it is available even if the pool becomes faulted. An administrator can provide additional information about a pool using this property. dedupratio The deduplication ratio specified for a pool, expressed as a multiplier. For example, a dedupratio value of 1.76 in- dicates that 1.76 units of data were stored but only 1 unit of disk space was actually consumed. See zfs(8) for a de- scription of the deduplication feature. free Number of blocks within the pool that are not allocated. freeing After a file system or snapshot is destroyed, the space it was using is returned to the pool asynchronously. freeing is the amount of space remaining to be reclaimed. Over time freeing will decrease while free increases. expandsize This property has currently no value on FreeBSD. guid A unique identifier for the pool. health The current health of the pool. Health can be "ONLINE", "DEGRADED", "FAULTED", "OFFLINE", "REMOVED", or "UNAVAIL". size Total size of the storage pool. unsupported@feature_guid Information about unsupported features that are enabled on the pool. See zpool-features(7) for details. used Amount of storage space used within the pool. The space usage properties report 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 character- istics of the data being written. In addition, ZFS reserves some space for internal accounting that the zfs(8) command takes into account, but the zpool(8) 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 no- ticeable. The following property can be set at creation time and import time: altroot Alternate root directory. If set, this directory is prepended to any mount points within the pool. This can be used when examining an unknown pool where the mount points cannot be trusted, or in an alternate boot environment, where the typical paths are not valid. altroot is not a persistent property. It is valid only while the system is up. Setting altroot defaults to using cachefile=none, though this may be overridden using an explicit setting. The following property can only be set at import time: readonly=on | off If set to on, pool will be imported in read-only mode with the fol- lowing restrictions: o Synchronous data in the intent log will not be accessible o Properties of the pool can not be changed o Datasets of this pool can only be mounted read-only o To write to a read-only pool, a export and import of the pool is required. The following properties can be set at creation time and import time, and later changed with the zpool set command: autoexpand=on | off Controls automatic pool expansion when the underlying LUN is grown. If set to "on", the pool will be resized according to the size of the expanded device. If the device is part of a mirror or raidz then all devices within that mirror/raidz group must be expanded before the new space is made available to the pool. The default be- havior is "off". This property can also be referred to by its shortened column name, expand. autoreplace=on | off Controls automatic device replacement. If set to "off", device re- placement must be initiated by the administrator by using the "zpool replace" command. If set to "on", any new device, found in the same physical location as a device that previously belonged to the pool, is automatically formatted and replaced. The default be- havior is "off". This property can also be referred to by its shortened column name, "replace". bootfs=pool/dataset Identifies the default bootable dataset for the root pool. This property is expected to be set mainly by the installation and up- grade programs. cachefile=path | none Controls the location of where the pool configuration is cached. Discovering all pools on system startup requires a cached copy of the configuration data that is stored on the root file system. All pools in this cache are automatically imported when the system boots. Some environments, such as install and clustering, need to cache this information in a different location so that pools are not automatically imported. Setting this property caches the pool configuration in a different location that can later be imported with "zpool import -c". Setting it to the special value "none" creates a temporary pool that is never cached, and the special value '' (empty string) uses the default location. comment=text A text string consisting of printable ASCII characters that will be stored such that it is available even if the pool becomes faulted. An administrator can provide additional information about a pool using this property. dedupditto=number Threshold for the number of block ditto copies. If the reference count for a deduplicated block increases above this number, a new ditto copy of this block is automatically stored. Default setting is 0. delegation=on | off Controls whether a non-privileged user is granted access based on the dataset permissions defined on the dataset. See zfs(8) for more information on ZFS delegated administration. failmode=wait | continue | panic Controls the system behavior in the event of catastrophic pool failure. This condition is typically a result of a loss of connec- tivity to the underlying storage device(s) or a failure of all de- vices within the pool. The behavior of such an event is determined as follows: wait Blocks all I/O access until the device connectivity is re- covered and the errors are cleared. This is the default behavior. continue Returns EIO to any new write I/O requests but allows reads to any of the remaining healthy devices. Any write requests that have yet to be committed to disk would be blocked. panic Prints out a message to the console and generates a system crash dump. feature@feature_name=enabled The value of this property is the current state of feature_name. The only valid value when setting this property is enabled which moves feature_name to the enabled state. See zpool-features(7) for details on feature states. listsnaps=on | off Controls whether information about snapshots associated with this pool is output when "zfs list" is run without the -t option. The default value is off. version=version The current on-disk version of the pool. This can be increased, but never decreased. The preferred method of updating pools is with the "zpool upgrade" command, though this property can be used when a specific version is needed for backwards compatibility. Once fea- ture flags is enabled on a pool this property will no longer have a value. 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 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 de- scribed in the "zpool create" subcommand. -f Forces use of vdev, 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 actu- ally 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. After a disk is in the pool, that disk can then be configured as a quorum device. zpool attach [-f] pool device new_device Attaches new_device to an existing zpool device. The existing de- vice cannot be part of a raidz configuration. If device is not cur- rently 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 clear [-F [-n]] 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 de- vice or devices are cleared. -F Initiates recovery mode for an unopenable pool. Attempts to discard the last few transactions in the pool to return it to an openable state. Not all damaged pools can be recov- ered by using this option. If successful, the data from the discarded transactions is irretrievably lost. -n Used in combination with the -F flag. Check whether dis- carding transactions would make the pool openable, but do not actually discard any transactions. zpool create [-fnd] [-o property=value] ... [-O file-system-property=value] ... [-m mountpoint] [-R root] 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", "spare" and "log" 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 overrid- den 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. By default all supported features are enabled on the new pool un- less the -d option is specified. -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 actu- ally creating the pool. The actual pool creation can still fail due to insufficient privileges or device sharing. -d Do not enable any features on the new pool. Individual features can be enabled by setting their corresponding properties to enabled with the -o option. See zpool-features(7) for details about feature properties. -o property=value [-o property=value] ... Sets the given pool properties. See the ""Properties"" sec- tion for a list of valid properties that can be set. -O file-system-property=value [-O file-system-property=value] ... Sets the given file system properties in the root file sys- tem of the pool. See zfs(8) Properties for a list of valid properties that can be set. -R root Equivalent to "-o cachefile=none,altroot=root" -m mountpoint Sets the mount point for the root dataset. The default mount point is "/pool" or "altroot/pool" if altroot is specified. The mount point must be an absolute path, "legacy", or "none". For more information on dataset mount points, see zfs(8). 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 detach pool device Detaches device from a mirror. The operation is refused if there are no other valid replicas of the data. 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 endi- anness) and imported as long as a sufficient number of devices are present. Before exporting the pool, all datasets within the pool are un- mounted. A pool can not be exported if it has a shared spare that is currently being used. 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 dif- ferent endianness will not recognize the disks. -f Forcefully unmount all datasets, using the "unmount -f" command. This command will forcefully export the pool even if it has a shared spare that is currently being used. This may lead to potential data corruption. zpool get all | property[,...] pool ... Retrieves the given list of properties (or all properties if "all" is used) for the specified storage pool(s). These properties are displayed with the following fields: name Name of storage pool property Property name value Property value source Property source, either 'default' or 'local'. See the ""Properties"" section for more information on the avail- able pool properties. zpool history [-il] [pool] ... Displays the command history of the specified pools or all pools if no pool is specified. -i Displays internally logged ZFS events in addition to user initiated events. -l Displays log records in long format, which in addition to standard format includes, the user name, the hostname, and the zone in which the operation was performed. zpool import [-d dir | -c cachefile] [-D] Lists pools available to import. If the -d option is not specified, this command searches for devices in "/dev". 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 dis- plays 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 avail- able. -c cachefile Reads configuration from the given cachefile that was cre- ated with the "cachefile" pool property. This cachefile is used instead of searching for devices. -d dir Searches for devices or files in dir. The -d option can be specified multiple times. -D Lists destroyed pools only. zpool import [-o mntopts] [-o property=value] ... [-d dir | -c cachefile] [-D] [-f] [-m] [-N] [-R root] [-F [-n]] -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. -o mntopts Comma-separated list of mount options to use when mounting datasets within the pool. See zfs(8) for a description of dataset properties and mount options. -o property=value Sets the specified property on the imported pool. See the ""Properties"" section for more information on the avail- able pool properties. -c cachefile Reads configuration from the given cachefile that was cre- ated with the "cachefile" pool property. This cachefile is used instead of searching for devices. -d dir Searches for devices or files in dir. The -d option can be specified multiple times. This option is incompatible with the -c option. -D Imports destroyed pools only. The -f option is also re- quired. -f Forces import, even if the pool appears to be potentially active. -m Enables import with missing log devices. -N Do not mount any filesystems from the imported pool. -R root Sets the "cachefile" property to "none" and the "altroot" property to "root" -F Recovery mode for a non-importable pool. Attempt to return the pool to an importable state by discarding the last few transactions. Not all damaged pools can be recovered by us- ing this option. If successful, the data from the discarded transactions is irretrievably lost. This option is ignored if the pool is importable or already imported. -n Used with the -F recovery option. Determines whether a non- importable pool can be made importable again, but does not actually perform the pool recovery. For more details about pool recovery mode, see the -F option, above. -a Searches for and imports all pools found. zpool import [-o mntopts] [-o property=value] ... [-d dir | -c cachefile] [-D] [-f] [-m] [-N] [-R root] [-F [-n]] 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 im- ported 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 de- termined if this was a failed export, or whether the device is re- ally in use from another host. To import a pool in this state, the -f option is required. -o mntopts Comma-separated list of mount options to use when mounting datasets within the pool. See zfs(8) for a description of dataset properties and mount options. -o property=value Sets the specified property on the imported pool. See the ""Properties"" section for more information on the avail- able pool properties. -c cachefile Reads configuration from the given cachefile that was cre- ated with the "cachefile" pool property. This cachefile is used instead of searching for devices. -d dir Searches for devices or files in dir. The -d option can be specified multiple times. This option is incompatible with the -c option. -D Imports destroyed pools only. The -f option is also re- quired. -f Forces import, even if the pool appears to be potentially active. -m Enables import with missing log devices. -N Do not mount any filesystems from the imported pool. -R root Equivalent to "-o cachefile=none,altroot=root" -F Recovery mode for a non-importable pool. Attempt to return the pool to an importable state by discarding the last few transactions. Not all damaged pools can be recovered by us- ing this option. If successful, the data from the discarded transactions is irretrievably lost. This option is ignored if the pool is importable or already imported. -n Used with the -F recovery option. Determines whether a non- importable pool can be made importable again, but does not actually perform the pool recovery. For more details about pool recovery mode, see the -F option, above. zpool iostat [-T d|u] [-v] [pool] ... [interval [count]] Displays I/O statistics for the given pools. When given an inter- val, 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. -T d|u Print a timestamp. Use modifier d for standard date format. See date(1). Use modifier u for unixtime (equals "date +%s"). -v Verbose statistics. Reports usage statistics for individual vdevs within the pool, in addition to the pool-wide statis- tics. zpool labelclear [-f] device Removes ZFS label information from the specified device. The device must not be part of an active pool configuration. -v Treat exported or foreign devices as inactive. zpool list [-Hv] [-o property[,...]] [-T d|u] [pool] ... [inverval [count]] Lists the given pools along with a health status and space usage. When given no arguments, all pools in the system are listed. When given an interval, the output is printed every interval sec- onds until Ctrl-C is pressed. If count is specified, the command exits after count reports are printed. -H Scripted mode. Do not display headers, and separate fields by a single tab instead of arbitrary space. -v Show more detailed information. -o property[,...] Comma-separated list of properties to display. See the ""Properties"" section for a list of valid properties. The default list is name, size, used, available, capacity, health, altroot. -T d|u Print a timestamp. Use modifier d for standard date format. See date(1). Use modifier u for unixtime (equals "date +%s"). 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. -t Temporary. Upon reboot, the specified physical device re- verts to its previous state. zpool online [-e] pool device ... Brings the specified physical device online. This command is not applicable to spares or cache devices. -e Expand the device to use all available space. If the device is part of a mirror or raidz then all devices must be ex- panded before the new space will become available to the pool. zpool reguid pool Generates a new unique identifier for the pool. You must ensure that all devices in this pool are online and healthy before per- forming this action. zpool remove pool device ... Removes the specified device from the pool. This command currently only supports removing hot spares, cache, and log devices. A mir- rored log device can be removed by specifying the top-level mirror for the log. Non-log devices that are part of a mirrored configura- tion can be removed using the "zpool detach" command. Non-redundant and raidz devices cannot be removed from a pool. zpool replace [-f] pool device [new_device] Replaces old_device with new_device. This is equivalent to attach- ing 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. new_device is required if the pool is not redundant. If new_device is not specified, it defaults to old_device. This form of replace- ment is useful after an existing disk has failed and has been phys- ically replaced. In this case, the new disk may have the same /dev 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 comple- tion. Scrubbing and resilvering are very similar operations. The differ- ence 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 fail- ure. 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 returns an error. To start a new scrub, you have to stop the old scrub with the "zpool scrub -s" command first. If a resilver is in progress, ZFS does not allow a scrub to be started until the resilver completes. -s Stop scrubbing. zpool set property=value pool Sets the given property on the specified pool. See the ""Properties"" section for more information on what properties can be set and acceptable values. zpool split [-n] [-R altroot] [-o mntopts] [-o property=value] pool newpool [device ...] Splits off one disk from each mirrored top-level vdev in a pool and creates a new pool from the split-off disks. The original pool must be made up of one or more mirrors and must not be in the process of resilvering. The split subcommand chooses the last device in each mirror vdev unless overridden by a device specification on the com- mand line. When using a device argument, split includes the specified de- vice(s) in a new pool and, should any devices remain unspecified, assigns the last device in each mirror vdev to that pool, as it does normally. If you are uncertain about the outcome of a split command, use the -n ("dry-run") option to ensure your command will have the effect you intend. -R altroot Automatically import the newly created pool after split- ting, using the specified altroot parameter for the new pool's alternate root. See the altroot description in the ""Properties"" section, above. -n Displays the configuration that would be created without actually splitting the pool. The actual pool split could still fail due to insufficient privileges or device status. -o mntopts Comma-separated list of mount options to use when mounting datasets within the pool. See zfs(8) for a description of dataset properties and mount options. Valid only in con- junction with the -R option. -o property=value Sets the specified property on the new pool. See the ""Properties"" section, above, for more information on the available pool properties. zpool status [-vx] [-T d|u] [pool] ... [interval [count]] Displays the detailed health status for the given pools. If no pool is specified, then the status of each pool in the system is dis- played. For more information on pool and device health, see the ""Device Failure and Recovery"" section. When given an interval, the output is printed every interval sec- onds until Ctrl-C is pressed. If count is specified, the command exits after count reports are printed. 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. Warnings about pools not using the latest on-disk format will not be included. -v Displays verbose data error information, printing out a complete list of all data errors since the last complete pool scrub. -T d|u Print a timestamp. Use modifier d for standard date format. See date(1). Use modifier u for unixtime (equals "date +%s"). zpool upgrade [-v] Displays pools which do not have all supported features enabled and pools formatted using a legacy ZFS version number. These pools can continue to be used, but some features may not be available. Use zpool upgrade -a to enable all features on all pools. -v Displays legacy ZFS versions supported by the current soft- ware. See zpool-features(7) for a description of feature flags features supported by the current software. zpool upgrade [-V version] -a | pool ... Enables all supported features on the given pool. Once this is done, the pool will no longer be accessible on systems that do not support feature flags. See zpool-features(7) for details on com- patability with system sthat support feature flags, but do not sup- port all features enabled on the pool. -a Enables all supported features on all pools. -V version Upgrade to the specified legacy version. If the -V flag is specified, no features will be enabled on the pool. This option can only be used to increase version number up to the last supported legacy version number. EXIT STATUS The following exit values are returned: 0 Successful completion. 1 An error occurred. 2 Invalid command line options were 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 da0 da1 da2 da3 da4 da5 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 da0 da1 mirror da2 da3 Example 3 Creating a ZFS Storage Pool by Using Partitions The following command creates an unmirrored pool using two GPT parti- tions. # zpool create tank da0p3 da1p3 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, as- suming 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 da2 da3 Example 6 Listing Available ZFS Storage Pools The following command lists all available pools on the system. # zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT pool 2.70T 473G 2.24T 17% 1.00x ONLINE - test 1.98G 89.5K 1.98G 0% 1.00x ONLINE - Example 7 Listing All Properties for a Pool The following command lists all the properties for a pool. # zpool get all pool pool size 2.70T - pool capacity 17% - pool altroot - default pool health ONLINE - pool guid 2501120270416322443 default pool version 28 default pool bootfs pool/root local pool delegation on default pool autoreplace off default pool cachefile - default pool failmode wait default pool listsnapshots off default pool autoexpand off default pool dedupditto 0 default pool dedupratio 1.00x - pool free 2.24T - pool allocated 473G - pool readonly off - Example 8 Destroying a ZFS Storage Pool The following command destroys the pool "tank" and any datasets con- tained within. # zpool destroy -f tank Example 9 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 10 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 da0 ONLINE da1 ONLINE Example 11 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 pool version 28. Example 12 Managing Hot Spares The following command creates a new pool with an available hot spare: # zpool create tank mirror da0 da1 spare da2 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 da0 da2 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 da2 Example 13 Creating a ZFS Pool with Mirrored Separate Intent Logs The following command creates a ZFS storage pool consisting of two, two-way mirrors and mirrored log devices: # zpool create pool mirror da0 da1 mirror da2 da3 log mirror da4 da5 Example 14 Adding Cache Devices to a ZFS Pool The following command adds two disks for use as cache devices to a ZFS storage pool: # zpool add pool cache da2 da3 Once added, the cache devices gradually fill with content from main memory. Depending on the size of your cache devices, it could take over an hour for them to fill. Capacity and reads can be monitored using the iostat subcommand as follows: # zpool iostat -v pool 5 Example 15 Removing a Mirrored Log Device The following command removes the mirrored log device mirror-2. Given this configuration: pool: tank state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM tank ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 da0 ONLINE 0 0 0 da1 ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 da2 ONLINE 0 0 0 da3 ONLINE 0 0 0 logs mirror-2 ONLINE 0 0 0 da4 ONLINE 0 0 0 da5 ONLINE 0 0 0 The command to remove the mirrored log mirror-2 is: # zpool remove tank mirror-2 Example 16 Recovering a Faulted ZFS Pool If a pool is faulted but recoverable, a message indicating this state is provided by "zpool status" if the pool was cached (see the -c cachefile argument above), or as part of the error output from a failed "zpool import" of the pool. Recover a cached pool with the "zpool clear" command: # zpool clear -F data Pool data returned to its state as of Tue Sep 08 13:23:35 2009. Discarded approximately 29 seconds of transactions. If the pool configuration was not cached, use "zpool import" with the recovery mode flag: # zpool import -F data Pool data returned to its state as of Tue Sep 08 13:23:35 2009. Discarded approximately 29 seconds of transactions. SEE ALSO zpool-features(7), zfs(8) AUTHORS This manual page is a mdoc(7) reimplementation of the OpenSolaris man- ual page zpool(1M), modified and customized for FreeBSD and licensed under the Common Development and Distribution License (CDDL). The mdoc(7) implementation of this manual page was initially written by Martin Matuska <mm@FreeBSD.org>. GNU March 14, 2013 ZPOOL(8)
NAME | SYNOPSIS | DESCRIPTION | SUBCOMMANDS | EXIT STATUS | EXAMPLES | SEE ALSO | AUTHORS
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