Solaris ZFS Administration Guide

Managing ZFS Storage Pool Properties

You can use the zpool get command to display pool property information. For example:

# zpool get all export
NAME     PROPERTY       VALUE       SOURCE
export   size           33.8G       -
export   capacity       0%          -
export   altroot        -           default
export   health         ONLINE      -
export   guid           2064230982813446135  default
export   version        22          default
export   bootfs         -           default
export   delegation     on          default
export   autoreplace    off         default
export   cachefile      -           default
export   failmode       wait        default
export   listsnapshots  off         default
export   autoexpand     off         default
export   dedupditto     0           default
export   dedupratio     3.00x       -
export   free           33.6G       -
export   allocated      105M        -

Storage pool properties can be set with the zpool set command. For example:

# zpool set autoreplace=on mpool
# zpool get autoreplace mpool
NAME  PROPERTY     VALUE    SOURCE
mpool autoreplace  on       default

Table 4–1 ZFS Pool Property Descriptions


Property Name	Type	Default Value	Description
`allocated`	String	N/A	Read-only value that identifies the amount of storage space within the pool that has been physically allocated.
`altroot`	String	off	Identifies an alternate root directory. If set, this directory is prepended to any mount points within the pool. This property can be used when examining an unknown pool, if the mount points cannot be trusted, or in an alternate boot environment, where the typical paths are not valid.
`autoreplace`	Boolean	`off`	Controls automatic device replacement. If set to off, device replacement must be initiated 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 behavior is off. This property can also be referred to by its shortened column name, `replace`.
`bootfs`	Boolean	N/A	Identifies the default bootable dataset for the root pool. This property is expected to be set mainly by the installation and upgrade programs.
`cachefile`	String	N/A	Controls where pool configuration information is cached. All pools in the cache are automatically imported when the system boots. However, installation and clustering environments might need to cache this information in a different location so that pools are not automatically imported. You can set this property to cache pool configuration in a different location that can be imported later by using the `zpool import` `-c` command. For most ZFS configurations, this property would not be used.
`capacity`	Number	N/A	Read-only value that identifies the percentage of pool space used. This property can also be referred to by its shortened column name, `cap`.
`dedupditto`	String	N/A	Sets a threshold, and if the reference count for a deduped block goes above the threshold, another ditto copy of the block is stored automatically. The default value is 0.
`dedupratio`	String	N/A	Read-only deduplication ratio specified for a pool, expressed as a multiplier.
`delegation`	Boolean	`on`	Controls whether a non-privileged user can be granted access permissions that are defined for the dataset. For more information, see Chapter 9, ZFS Delegated Administration.
`failmode`	String	`wait`	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 by one of the following values: `wait`, blocks all I/O requests to the pool until the device connectivity is restored and the errors are cleared by using the `zpool clear` command. This is the default behavior. In this state, I/O operations to the pool are blocked, but read operations might succeed. A pool remains in the wait state until the device issue is resolved; `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. After the device is reconnected or replaced, the errors must be cleared with the `zpool clear` command; `panic`, prints out a message to the console and generates a system crash dump.
`free`	String	N/A	Read-only value that identifies the number of blocks within the pool that are not allocated.
`guid`	String	N/A	Read-only property that identifies the unique identifier for the pool.
`health`	String	N/A	Read-only property that identifies the current health of the pool, as either ONLINE, DEGRADED, FAULTED, OFFLINE, REMOVED, or UNAVAIL.
`listsnapshots`	String	off	Controls whether snapshot information that is associated with this pool is displayed with the `zfs list` command. If this property is disabled, snapshot information can be displayed with the `zfs list` `-t snapshot` command. The default value is `off`.
`size`	Number	N/A	Read-only property that identifies the total size of the storage pool.
`used`	Number	N/A	Read-only property that identifies the amount of storage space used within the pool.
`version`	Number	N/A	Identifies the current on-disk version of the pool. The preferred method of updating pools is with the `zpool upgrade` command, although this property can be used when a specific version is needed for backwards compatibility. This property can be set to any number between 1 and the current version reported by the `zpool upgrade` `-v` command. The `current` value is an alias for the latest supported version.