Managing ZFS Storage Pool Properties

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

# zpool get all zeepool
NAME     PROPERTY       VALUE                SOURCE
zeepool  allocated      6.29G                -
zeepool  altroot        -                    default
zeepool  autoexpand     off                  default
zeepool  autoreplace    off                  default
zeepool  bootfs         -                    default
zeepool  cachefile      -                    default
zeepool  capacity       1%                   -
zeepool  dedupditto     0                    default
zeepool  dedupratio     1.00x                -
zeepool  delegation     on                   default
zeepool  failmode       wait                 default
zeepool  free           550G                 -
zeepool  guid           7543986419840620672  -
zeepool  health         ONLINE               -
zeepool  listshares     off                  default
zeepool  listsnapshots  off                  default
zeepool  readonly       off                  -
zeepool  size           556G                 -
zeepool  version        34                   default

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

# zpool set autoreplace=on zeepool
# zpool get autoreplace zeepool
NAME     PROPERTY     VALUE    SOURCE
zeepool  autoreplace  on       local

If you attempt to set a pool property on a pool that is 100% full, you will see a message similar to the following:

# zpool set autoreplace=on tank
cannot set property for 'tank': out of space

For information on preventing pool space capacity problems, see Chapter 11, Recommended Oracle Solaris ZFS Practices.

Table 3-1 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 you are 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 property abbreviation is `replace`.
`bootfs`	Boolean	N/A	Identifies the default bootable file system for the root pool. This property is typically set by the installation 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 require this information to be cached in a different location so that pools are not automatically imported. You can set this property to cache pool configuration information in a different location. This information can be imported later by using the `zpool import` `–c` command. For most ZFS configurations, this property is not used.
`capacity`	Number	N/A	Read-only value that identifies the percentage of pool space used. The property abbreviation is `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.
`dedupratio`	String	N/A	Read-only deduplication ratio achieved for a pool, expressed as a multiplier.
`delegation`	Boolean	`on`	Controls whether a nonprivileged user can be granted access permissions that are defined for a file system. For more information, see Chapter 8, Oracle Solaris ZFS Delegated Administration.
`failmode`	String	`wait`	Controls the system behavior if a catastrophic pool failure occurs. This condition is typically a result of a loss of connectivity to the underlying storage device or devices 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 device connectivity is restored, and the errors are cleared by using the `zpool clear` command. 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 an EIO error 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 are blocked. After the device is reconnected or replaced, the errors must be cleared with the `zpool clear` command. `panic` – Prints 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, SUSPENDED, REMOVED, or UNAVAIL.
`listshares`	String	off	Controls whether share information in this pool is displayed with the `zfs list` command. The default value is `off`.
`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.
`readonly`	Boolean	off	Identifies whether a pool can be modified. This property is only enabled when a pool is has been imported in read-only mode. If enabled, any synchronous data that exists only in the intent log will not be accessible until the pool is re-imported in read-write mode.
`size`	Number	N/A	Read-only property that identifies the total size of the storage 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.