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zpool.8
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'\" te
.\" Copyright (c) 2007, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 2011 Nexenta Systems, Inc. All rights reserved.
.\" Copyright (c) 2013 by Delphix. All rights reserved.
.\" Copyright (c) 2012 Cyril Plisko. All Rights Reserved.
.\" The contents of this file are subject to the terms of the Common Development
.\" and Distribution License (the "License"). You may not use this file except
.\" in compliance with the License. You can obtain a copy of the license at
.\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
.\"
.\" See the License for the specific language governing permissions and
.\" limitations under the License. When distributing Covered Code, include this
.\" CDDL HEADER in each file and include the License file at
.\" usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this
.\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your
.\" own identifying information:
.\" Portions Copyright [yyyy] [name of copyright owner]
.TH zpool 8 "14 December 2012" "ZFS pool 28, filesystem 5" "System Administration Commands"
.SH NAME
zpool \- configures ZFS storage pools
.SH SYNOPSIS
.LP
.nf
\fBzpool\fR [\fB-?\fR]
.fi
.LP
.nf
\fBzpool add\fR [\fB-fgLnP\fR] [\fB-o\fR \fIproperty=value\fR] \fIpool\fR \fIvdev\fR ...
.fi
.LP
.nf
\fBzpool attach\fR [\fB-f\fR] [\fB-o\fR \fIproperty=value\fR] \fIpool\fR \fIdevice\fR \fInew_device\fR
.fi
.LP
.nf
\fBzpool clear\fR \fIpool\fR [\fIdevice\fR]
.fi
.LP
.nf
\fBzpool create\fR [\fB-fnd\fR] [\fB-o\fR \fIproperty=value\fR] ... [\fB-O\fR \fIfile-system-property=value\fR]
... [\fB-m\fR \fImountpoint\fR] [\fB-R\fR \fIroot\fR] [\fB-t\fR \fItname\fR] \fIpool\fR \fIvdev\fR ...
.fi
.LP
.nf
\fBzpool destroy\fR [\fB-f\fR] \fIpool\fR
.fi
.LP
.nf
\fBzpool detach\fR \fIpool\fR \fIdevice\fR
.fi
.LP
.nf
\fBzpool events\fR [\fB-vHfc\fR] [\fIpool\fR] ...
.fi
.LP
.nf
\fBzpool export\fR [\fB-a\fR] [\fB-f\fR] \fIpool\fR ...
.fi
.LP
.nf
\fBzpool get\fR [\fB-pH\fR] "\fIall\fR" | \fIproperty\fR[,...] \fIpool\fR ...
.fi
.LP
.nf
\fBzpool history\fR [\fB-il\fR] [\fIpool\fR] ...
.fi
.LP
.nf
\fBzpool import\fR [\fB-d\fR \fIdir\fR] [\fB-D\fR]
.fi
.LP
.nf
\fBzpool import\fR [\fB-o \fImntopts\fR\fR] [\fB-o\fR \fIproperty=value\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR]
[\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-N\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR] [\fB-X\fR\] [\fB-T\fR\]] \fB-a\fR
.fi
.LP
.nf
\fBzpool import\fR [\fB-o \fImntopts\fR\fR] [\fB-o\fR \fIproperty=value\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR]
[\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR] [\fB-X\fR] [\fB-T\fR\]] [\fB-t\fR]] \fIpool\fR |\fIid\fR [\fInewpool\fR]
.fi
.LP
.nf
\fBzpool iostat\fR [\fB-T\fR d | u ] [\fB-gLPvy\fR] [\fIpool\fR] ... [\fIinterval\fR[\fIcount\fR]]
.fi
.LP
.nf
\fBzpool labelclear\fR [\fB-f\fR] \fIdevice\fR
.fi
.LP
.nf
\fBzpool list\fR [\fB-T\fR d | u ] [\fB-HgLPv\fR] [\fB-o\fR \fIproperty\fR[,...]] [\fIpool\fR] ...
[\fIinterval\fR[\fIcount\fR]]
.fi
.LP
.nf
\fBzpool offline\fR [\fB-t\fR] \fIpool\fR \fIdevice\fR ...
.fi
.LP
.nf
\fBzpool online\fR \fIpool\fR \fIdevice\fR ...
.fi
.LP
.nf
\fBzpool reguid\fR \fIpool\fR
.fi
.LP
.nf
\fBzpool reopen\fR \fIpool\fR
.fi
.LP
.nf
\fBzpool remove\fR \fIpool\fR \fIdevice\fR ...
.fi
.LP
.nf
\fBzpool replace\fR [\fB-f\fR] [\fB-o\fR \fIproperty=value\fR] \fIpool\fR \fIdevice\fR [\fInew_device\fR]
.fi
.LP
.nf
\fBzpool scrub\fR [\fB-s\fR] \fIpool\fR ...
.fi
.LP
.nf
\fBzpool set\fR \fIproperty\fR=\fIvalue\fR \fIpool\fR
.fi
.LP
.nf
\fBzpool split\fR [\fB-gLnP\fR] [\fB-R\fR \fIaltroot\fR] [\fB-o\fR \fIproperty=value\fR] \fIpool\fR \fInewpool\fR [\fIdevice\fR ...]
.fi
.LP
.nf
\fBzpool status\fR [\fB-gLPvxD\fR] [\fB-T\fR d | u] [\fIpool\fR] ... [\fIinterval\fR [\fIcount\fR]]
.fi
.LP
.nf
\fBzpool upgrade\fR
.fi
.LP
.nf
\fBzpool upgrade\fR \fB-v\fR
.fi
.LP
.nf
\fBzpool upgrade\fR [\fB-V\fR \fIversion\fR] \fB-a\fR | \fIpool\fR ...
.fi
.SH DESCRIPTION
.sp
.LP
The \fBzpool\fR command configures \fBZFS\fR storage pools. A storage pool is a collection of devices that provides physical storage and data replication for \fBZFS\fR datasets.
.sp
.LP
All datasets within a storage pool share the same space. See \fBzfs\fR(8) for information on managing datasets.
.SS "Virtual Devices (\fBvdev\fRs)"
.sp
.LP
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:
.sp
.ne 2
.mk
.na
\fB\fBdisk\fR\fR
.ad
.RS 10n
.rt
A block device, typically located under \fB/dev\fR. \fBZFS\fR can use individual 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"). For example, "sda" is equivalent to "/dev/sda". A whole disk can be specified by omitting the partition designation. When given a whole disk, \fBZFS\fR automatically labels the disk, if necessary.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfile\fR\fR
.ad
.RS 10n
.rt
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.
.RE
.sp
.ne 2
.mk
.na
\fB\fBmirror\fR\fR
.ad
.RS 10n
.rt
A mirror of two or more devices. Data is replicated in an identical fashion across all components of a mirror. A mirror with \fIN\fR disks of size \fIX\fR can hold \fIX\fR bytes and can withstand (\fIN-1\fR) devices failing before data integrity is compromised.
.RE
.sp
.ne 2
.mk
.na
\fB\fBraidz\fR\fR
.ad
.br
.na
\fB\fBraidz1\fR\fR
.ad
.br
.na
\fB\fBraidz2\fR\fR
.ad
.br
.na
\fB\fBraidz3\fR\fR
.ad
.RS 10n
.rt
A variation on \fBRAID-5\fR that allows for better distribution of parity and eliminates the "\fBRAID-5\fR write hole" (in which data and parity become inconsistent after a power loss). Data and parity is striped across all disks within a \fBraidz\fR group.
.sp
A \fBraidz\fR group can have single-, double- , or triple parity, meaning that the \fBraidz\fR group can sustain one, two, or three failures, respectively, without losing any data. The \fBraidz1\fR \fBvdev\fR type specifies a single-parity \fBraidz\fR group; the \fBraidz2\fR \fBvdev\fR type specifies a double-parity \fBraidz\fR group; and the \fBraidz3\fR \fBvdev\fR type specifies a triple-parity \fBraidz\fR group. The \fBraidz\fR \fBvdev\fR type is an alias for \fBraidz1\fR.
.sp
A \fBraidz\fR group with \fIN\fR disks of size \fIX\fR with \fIP\fR parity disks can hold approximately (\fIN-P\fR)*\fIX\fR bytes and can withstand \fIP\fR device(s) failing before data integrity is compromised. The minimum number of devices in a \fBraidz\fR group is one more than the number of parity disks. The recommended number is between 3 and 9 to help increase performance.
.RE
.sp
.ne 2
.mk
.na
\fB\fBspare\fR\fR
.ad
.RS 10n
.rt
A special pseudo-\fBvdev\fR which keeps track of available hot spares for a pool. For more information, see the "Hot Spares" section.
.RE
.sp
.ne 2
.mk
.na
\fB\fBlog\fR\fR
.ad
.RS 10n
.rt
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, \fBraidz\fR \fBvdev\fR types are not supported for the intent log. For more information, see the "Intent Log" section.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcache\fR\fR
.ad
.RS 10n
.rt
A device used to cache storage pool data. A cache device cannot be configured as a mirror or \fBraidz\fR group. For more information, see the "Cache Devices" section.
.RE
.sp
.LP
Virtual devices cannot be nested, so a mirror or \fBraidz\fR virtual device can only contain files or disks. Mirrors of mirrors (or other combinations) are not allowed.
.sp
.LP
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, \fBZFS\fR automatically places data on the newly available devices.
.sp
.LP
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:
.sp
.in +2
.nf
# \fBzpool create mypool mirror sda sdb mirror sdc sdd\fR
.fi
.in -2
.sp
.SS "Device Failure and Recovery"
.sp
.LP
\fBZFS\fR supports a rich set of mechanisms for handling device failure and data corruption. All metadata and data is checksummed, and \fBZFS\fR automatically repairs bad data from a good copy when corruption is detected.
.sp
.LP
In order to take advantage of these features, a pool must make use of some form of redundancy, using either mirrored or \fBraidz\fR groups. While \fBZFS\fR 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.
.sp
.LP
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 corrupted metadata, or one or more faulted devices, and insufficient replicas to continue functioning.
.sp
.LP
The health of the top-level vdev, such as mirror or \fBraidz\fR 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 following states:
.sp
.ne 2
.mk
.na
\fB\fBDEGRADED\fR\fR
.ad
.RS 12n
.rt
One or more top-level vdevs is in the degraded state because one or more component devices are offline. Sufficient replicas exist to continue functioning.
.sp
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:
.RS +4
.TP
.ie t \(bu
.el o
The number of checksum errors exceeds acceptable levels and the device is degraded as an indication that something may be wrong. \fBZFS\fR continues to use the device as necessary.
.RE
.RS +4
.TP
.ie t \(bu
.el 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.
.RE
.RE
.sp
.ne 2
.mk
.na
\fB\fBFAULTED\fR\fR
.ad
.RS 12n
.rt
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.
.sp
One or more component devices is in the faulted state, and insufficient replicas exist to continue functioning. The underlying conditions are as follows:
.RS +4
.TP
.ie t \(bu
.el o
The device could be opened, but the contents did not match expected values.
.RE
.RS +4
.TP
.ie t \(bu
.el o
The number of I/O errors exceeds acceptable levels and the device is faulted to prevent further use of the device.
.RE
.RE
.sp
.ne 2
.mk
.na
\fB\fBOFFLINE\fR\fR
.ad
.RS 12n
.rt
The device was explicitly taken offline by the "\fBzpool offline\fR" command.
.RE
.sp
.ne 2
.mk
.na
\fB\fBONLINE\fR\fR
.ad
.RS 12n
.rt
The device is online and functioning.
.RE
.sp
.ne 2
.mk
.na
\fB\fBREMOVED\fR\fR
.ad
.RS 12n
.rt
The device was physically removed while the system was running. Device removal detection is hardware-dependent and may not be supported on all platforms.
.RE
.sp
.ne 2
.mk
.na
\fB\fBUNAVAIL\fR\fR
.ad
.RS 12n
.rt
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.
.RE
.sp
.LP
If a device is removed and later re-attached to the system, \fBZFS\fR attempts to put the device online automatically. Device attach detection is hardware-dependent and might not be supported on all platforms.
.SS "Hot Spares"
.sp
.LP
\fBZFS\fR 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" \fBvdev\fR with any number of devices. For example,
.sp
.in +2
.nf
# zpool create pool mirror sda sdb spare sdc sdd
.fi
.in -2
.sp
.sp
.LP
Spares can be shared across multiple pools, and can be added with the "\fBzpool add\fR" command and removed with the "\fBzpool remove\fR" command. Once a spare replacement is initiated, a new "spare" \fBvdev\fR is created within the configuration that will remain there until the original device is replaced. At this point, the hot spare becomes available again.
.sp
.LP
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.
.sp
.LP
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.
.sp
.LP
Spares cannot replace log devices.
.SS "Intent Log"
.sp
.LP
The \fBZFS\fR Intent Log (\fBZIL\fR) satisfies \fBPOSIX\fR requirements for synchronous transactions. For instance, databases often require their transactions to be on stable storage devices when returning from a system call. \fBNFS\fR and other applications can also use \fBfsync\fR() 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 \fBNVRAM\fR or a dedicated disk. For example:
.sp
.in +2
.nf
\fB# zpool create pool sda sdb log sdc\fR
.fi
.in -2
.sp
.sp
.LP
Multiple log devices can also be specified, and they can be mirrored. See the EXAMPLES section for an example of mirroring multiple log devices.
.sp
.LP
Log devices can be added, replaced, attached, detached, and imported and exported as part of the larger pool. Mirrored log devices can be removed by specifying the top-level mirror for the log.
.SS "Cache Devices"
.sp
.LP
Devices can be added to a storage pool as "cache devices." These devices 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 allow 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.
.sp
.LP
To create a pool with cache devices, specify a "cache" \fBvdev\fR with any number of devices. For example:
.sp
.in +2
.nf
\fB# zpool create pool sda sdb cache sdc sdd\fR
.fi
.in -2
.sp
.sp
.LP
Cache devices cannot be mirrored or part of a \fBraidz\fR configuration. If a read error is encountered on a cache device, that read \fBI/O\fR is reissued to the original storage pool device, which might be part of a mirrored or \fBraidz\fR configuration.
.sp
.LP
The content of the cache devices is considered volatile, as is the case with other system caches.
.SS "Properties"
.sp
.LP
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:
.sp
.ne 2
.mk
.na
\fB\fBavailable\fR\fR
.ad
.RS 20n
.rt
Amount of storage available within the pool. This property can also be referred to by its shortened column name, "avail".
.RE
.sp
.ne 2
.mk
.na
\fB\fBcapacity\fR\fR
.ad
.RS 20n
.rt
Percentage of pool space used. This property can also be referred to by its shortened column name, "cap".
.RE
.sp
.ne 2
.mk
.na
\fB\fBexpandsize\fR\fR
.ad
.RS 20n
.rt
Amount of uninitialized space within the pool or device that can be used to
increase the total capacity of the pool. Uninitialized space consists of
any space on an EFI labeled vdev which has not been brought online
(i.e. zpool online -e). This space occurs when a LUN is dynamically expanded.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfragmentation\fR\fR
.ad
.RS 20n
.rt
The amount of fragmentation in the pool.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfree\fR\fR
.ad
.RS 20n
.rt
The amount of free space available in the pool.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfreeing\fR\fR
.ad
.RS 20n
.rt
After a file system or snapshot is destroyed, the space it was using is
returned to the pool asynchronously. \fB\fBfreeing\fR\fR is the amount of
space remaining to be reclaimed. Over time \fB\fBfreeing\fR\fR will decrease
while \fB\fBfree\fR\fR increases.
.RE
.sp
.ne 2
.mk
.na
\fB\fBhealth\fR\fR
.ad
.RS 20n
.rt
The current health of the pool. Health can be "\fBONLINE\fR", "\fBDEGRADED\fR", "\fBFAULTED\fR", " \fBOFFLINE\fR", "\fBREMOVED\fR", or "\fBUNAVAIL\fR".
.RE
.sp
.ne 2
.mk
.na
\fB\fBguid\fR\fR
.ad
.RS 20n
.rt
A unique identifier for the pool.
.RE
.sp
.ne 2
.mk
.na
\fB\fBsize\fR\fR
.ad
.RS 20n
.rt
Total size of the storage pool.
.RE
.sp
.ne 2
.mk
.na
\fB\fBunsupported@\fR\fIfeature_guid\fR\fR
.ad
.RS 20n
.rt
.sp
Information about unsupported features that are enabled on the pool. See
\fBzpool-features\fR(5) for details.
.RE
.sp
.ne 2
.mk
.na
\fB\fBused\fR\fR
.ad
.RS 20n
.rt
Amount of storage space used within the pool.
.RE
.sp
.LP
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 \fBraidz\fR configuration depends on the characteristics of the data being written. In addition, \fBZFS\fR reserves some space for internal accounting that the \fBzfs\fR(8) command takes into account, but the \fBzpool\fR 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.
.sp
.LP
The following property can be set at creation time:
.sp
.ne 2
.mk
.na
\fB\fBashift\fR\fR
.ad
.sp .6
.RS 4n
Pool sector size exponent, to the power of 2 (internally referred to as "ashift"). I/O operations will be aligned to the specified size boundaries. Additionally, the minimum (disk) write size will be set to the specified size, so this represents a space vs. performance trade-off. The typical case for setting this property is when performance is important and the underlying disks use 4KiB sectors but report 512B sectors to the OS (for compatibility reasons); in that case, set \fBashift=12\fR (which is 1<<12 = 4096).
.LP
For optimal performance, the pool sector size should be greater than or equal to the sector size of the underlying disks. Since the property cannot be changed after pool creation, if in a given pool, you \fIever\fR want to use drives that \fIreport\fR 4KiB sectors, you must set \fBashift=12\fR at pool creation time.
.LP
Keep in mind is that the \fBashift\fR is \fIvdev\fR specific and is not a \fIpool\fR global. This means that when adding new vdevs to an existing pool you may need to specify the \fBashift\fR.
.RE
.sp
.LP
The following property can be set at creation time and import time:
.sp
.ne 2
.mk
.na
\fB\fBaltroot\fR\fR
.ad
.sp .6
.RS 4n
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. \fBaltroot\fR is not a persistent property. It is valid only while the system is up. Setting \fBaltroot\fR defaults to using \fBcachefile\fR=none, though this may be overridden using an explicit setting.
.RE
.sp
.LP
The following property can only be set at import time:
.sp
.ne 2
.mk
.na
\fB\fBreadonly\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
If set to \fBon\fR, the pool will be imported in read-only mode: Synchronous data in the intent log will not be accessible, properties of the pool can not be changed and datasets of the pool can only be mounted read-only. The \fBreadonly\fR property of its datasets will be implicitly set to \fBon\fR.
It can also be specified by its column name of \fBrdonly\fR.
To write to a read-only pool, a export and import of the pool is required.
.RE
.sp
.LP
The following properties can be set at creation time and import time, and later changed with the \fBzpool set\fR command:
.sp
.ne 2
.mk
.na
\fB\fBautoexpand\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
Controls automatic pool expansion when the underlying LUN is grown. If set to \fBon\fR, the pool will be resized according to the size of the expanded device. If the device is part of a mirror or \fBraidz\fR then all devices within that mirror/\fBraidz\fR group must be expanded before the new space is made available to the pool. The default behavior is \fBoff\fR. This property can also be referred to by its shortened column name, \fBexpand\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBautoreplace\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
Controls automatic device replacement. If set to "\fBoff\fR", device replacement must be initiated by the administrator by using the "\fBzpool replace\fR" command. If set to "\fBon\fR", 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 behavior is "\fBoff\fR". This property can also be referred to by its shortened column name, "replace".
.RE
.sp
.ne 2
.mk
.na
\fB\fBbootfs\fR=\fIpool\fR/\fIdataset\fR\fR
.ad
.sp .6
.RS 4n
Identifies the default bootable dataset for the root pool. This property is expected to be set mainly by the installation and upgrade programs.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcachefile\fR=\fIpath\fR | \fBnone\fR\fR
.ad
.sp .6
.RS 4n
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 "\fBzpool import -c\fR". Setting it to the special value "\fBnone\fR" creates a temporary pool that is never cached, and the special value \fB\&''\fR (empty string) uses the default location.
.sp
Multiple pools can share the same cache file. Because the kernel destroys and recreates this file when pools are added and removed, care should be taken when attempting to access this file. When the last pool using a \fBcachefile\fR is exported or destroyed, the file is removed.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcomment\fR=\fB\fItext\fR\fR
.ad
.sp .6
.RS 4n
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.
.RE
.sp
.ne 2
.mk
.na
\fB\fBdedupditto\fR=\fB\fInumber\fR\fR
.ad
.sp .6
.RS 4n
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. The default setting is 0 which causes no ditto copies to be created for deduplicated blocks. The miniumum legal nonzero setting is 100.
.RE
.sp
.ne 2
.mk
.na
\fB\fBdelegation\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
Controls whether a non-privileged user is granted access based on the dataset permissions defined on the dataset. See \fBzfs\fR(8) for more information on \fBZFS\fR delegated administration.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfailmode\fR=\fBwait\fR | \fBcontinue\fR | \fBpanic\fR\fR
.ad
.sp .6
.RS 4n
Controls the system behavior in the event of catastrophic pool failure. This condition is typically a result of a loss of connectivity to the underlying storage device(s) or a failure of all devices within the pool. The behavior of such an event is determined as follows:
.sp
.ne 2
.mk
.na
\fB\fBwait\fR\fR
.ad
.RS 12n
.rt
Blocks all \fBI/O\fR access until the device connectivity is recovered and the errors are cleared. This is the default behavior.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcontinue\fR\fR
.ad
.RS 12n
.rt
Returns \fBEIO\fR to any new write \fBI/O\fR 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.
.RE
.sp
.ne 2
.mk
.na
\fB\fBpanic\fR\fR
.ad
.RS 12n
.rt
Prints out a message to the console and generates a system crash dump.
.RE
.RE
.sp
.ne 2
.na
\fB\fBfeature@\fR\fIfeature_name\fR=\fBenabled\fR\fR
.ad
.RS 4n
The value of this property is the current state of \fIfeature_name\fR. The
only valid value when setting this property is \fBenabled\fR which moves
\fIfeature_name\fR to the enabled state. See \fBzpool-features\fR(5) for
details on feature states.
.RE
.sp
.ne 2
.mk
.na
\fB\fBlistsnaps\fR=on | off\fR
.ad
.sp .6
.RS 4n
Controls whether information about snapshots associated with this pool is output when "\fBzfs list\fR" is run without the \fB-t\fR option. The default value is "off".
.RE
.sp
.ne 2
.mk
.na
\fB\fBversion\fR=\fIversion\fR\fR
.ad
.sp .6
.RS 4n
The current on-disk version of the pool. This can be increased, but never decreased. The preferred method of updating pools is with the "\fBzpool upgrade\fR" command, though this property can be used when a specific version is needed for backwards compatibility. Once feature flags are enabled on a pool this property will no longer have a value.
.RE
.SS "Subcommands"
.sp
.LP
All subcommands that modify state are logged persistently to the pool in their original form.
.sp
.LP
The \fBzpool\fR 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:
.sp
.ne 2
.mk
.na
\fB\fBzpool\fR \fB-?\fR\fR
.ad
.sp .6
.RS 4n
Displays a help message.
.RE
.sp
.ne 2
.mk
.na
\fB\fBzpool add\fR [\fB-fgLnP\fR] [\fB-o\fR \fIproperty=value\fR] \fIpool\fR \fIvdev\fR ...\fR
.ad
.sp .6
.RS 4n
Adds the specified virtual devices to the given pool. The \fIvdev\fR specification is described in the "Virtual Devices" section. The behavior of the \fB-f\fR option, and the device checks performed are described in the "zpool create" subcommand.
.sp
.ne 2
.mk
.na
\fB\fB-f\fR\fR
.ad
.RS 6n
.rt
Forces use of \fBvdev\fRs, even if they appear in use or specify a conflicting replication level. Not all devices can be overridden in this manner.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-g\fR\fR
.ad
.RS 6n
.rt
Display vdev GUIDs instead of the normal device names. These GUIDs can be used in place of device names for the zpool detach/offline/remove/replace commands.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-L\fR\fR
.ad
.RS 6n
.rt
Display real paths for vdevs resolving all symbolic links. This can be used to look up the current block device name regardless of the /dev/disk/ path used to open it.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-n\fR\fR
.ad
.RS 6n
.rt
Displays the configuration that would be used without actually adding the \fBvdev\fRs. The actual pool creation can still fail due to insufficient privileges or device sharing.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-P\fR\fR
.ad
.RS 6n
.rt
Display full paths for vdevs instead of only the last component of the path. This can be used in conjunction with the \fB-L\fR flag.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-o\fR \fIproperty=value\fR
.ad
.sp .6
.RS 4n
Sets the given pool properties. See the "Properties" section for a list of valid properties that can be set. The only property supported at the moment is \fBashift\fR. \fBDo note\fR that some properties (among them \fBashift\fR) are \fInot\fR inherited from a previous vdev. They are vdev specific, not pool specific.
.RE
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.
.RE
.sp
.ne 2
.mk
.na
\fB\fBzpool attach\fR [\fB-f\fR] [\fB-o\fR \fIproperty=value\fR] \fIpool\fR \fIdevice\fR \fInew_device\fR\fR
.ad
.sp .6
.RS 4n
Attaches \fInew_device\fR to an existing \fBzpool\fR device. The existing device cannot be part of a \fBraidz\fR configuration. If \fIdevice\fR is not currently part of a mirrored configuration, \fIdevice\fR automatically transforms into a two-way mirror of \fIdevice\fR and \fInew_device\fR. If \fIdevice\fR is part of a two-way mirror, attaching \fInew_device\fR creates a three-way mirror, and so on. In either case, \fInew_device\fR begins to resilver immediately.
.sp
.ne 2
.mk
.na
\fB\fB-f\fR\fR
.ad
.RS 6n
.rt
Forces use of \fInew_device\fR, even if its appears to be in use. Not all devices can be overridden in this manner.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-o\fR \fIproperty=value\fR
.ad
.sp .6
.RS 4n
Sets the given pool properties. See the "Properties" section for a list of valid properties that can be set. The only property supported at the moment is "ashift".
.RE
.RE
.sp
.ne 2
.mk
.na
\fB\fBzpool clear\fR \fIpool\fR [\fIdevice\fR] ...\fR
.ad
.sp .6
.RS 4n
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.
.RE
.sp
.ne 2
.mk
.na
\fB\fBzpool create\fR [\fB-fnd\fR] [\fB-o\fR \fIproperty=value\fR] ... [\fB-O\fR \fIfile-system-property=value\fR] ... [\fB-m\fR \fImountpoint\fR] [\fB-R\fR \fIroot\fR] [\fB-t\fR \fItname\fR] \fIpool\fR \fIvdev\fR ...\fR
.ad
.sp .6
.RS 4n
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 ("-"), period ("."), colon (":"), and space (" "). The pool names "mirror", "raidz", "spare" and "log" are reserved, as are names beginning with the pattern "c[0-9]". The \fBvdev\fR specification is described in the "Virtual Devices" section.
.sp
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 \fBZFS\fR. Other uses, such as having a preexisting \fBUFS\fR file system, can be overridden with the \fB-f\fR option.
.sp
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 \fB-f\fR is specified. The use of differently sized devices within a single \fBraidz\fR or mirror group is also flagged as an error unless \fB-f\fR is specified.
.sp
Unless the \fB-R\fR option is specified, the default mount point is "/\fIpool\fR". The mount point must not exist or must be empty, or else the root dataset cannot be mounted. This can be overridden with the \fB-m\fR option.
.sp
By default all supported features are enabled on the new pool unless the \fB-d\fR option is specified.
.sp
.ne 2
.mk
.na
\fB\fB-f\fR\fR
.ad
.sp .6
.RS 4n
Forces use of \fBvdev\fRs, even if they appear in use or specify a conflicting replication level. Not all devices can be overridden in this manner.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-n\fR\fR
.ad
.sp .6
.RS 4n
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.
.RE
.sp
.ne 2
.mk
.na
\fB\fB-d\fR\fR