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Managing Pools

  4 minute read.

Last Modified 2022-07-29 16:33 EDT

Use the Pool Operations icon button to manage a pool. Click to display the Pool Actions dropdown list.


The options on the Pool Actions dropdown list vary based on the pool setup. Only pools with encryption include the Encryption Actions Export Dataset Keys option.

Setting Up Auto TRIM

Select Pool Options to display the Edit Pool Options dialog for the selected pool.


Select Auto TRIM.

Select Confirm and then Save.

With Auto TRIM selected and active, TrueNAS periodically checks the pool disks for storage blocks it can reclaim. Auto TRIM can impact pool performance, so the default setting is disabled.

For more details about TRIM in ZFS, see the autotrim property description in zpool.8.

Exporting or Disconnecting a Pool

The Export/Disconnect option disconnects the pool to transfer drives to a new system where you can import the pool. Also use to completely delete the pool and any data stored on it.

Select Export/Disconnect on the Pool Actions dropdown list for the selected pool.


A dialog box displays with any system services affected by exporting the pool listed in the dialog.

Select Destroy data on this pool? to erase all data on the pool.

Click Delete configuration of shares that used this pool? to delete shares connected to the pool.

Adding Vdevs

ZFS supports adding vdevs to an existing ZFS pool to increase the capacity of the pool. Use Add Vdevs to expand the storage of an existing vdev. After creating a vdev, you cannot add more drives to that vdev but you can stripe a new vdev with another of the same type to increase the overall pool size. To extend a pool, you must add a vdev that is the same type as existing vdevs.

Vdevs extending examples:

  • To make a striped mirror, add the same number of drives to extend a ZFS mirror. For example, you start with ten available drives. Begin by creating a mirror of two drives, and then extending the mirror by adding another mirror of two drives. Repeat this three more times until you add all ten drives.
  • To make a stripe of two RAIDZ1 vdevs (similar to RAID 50 on a hardware controller), add another three drives to extend the three-drive RAIDZ1.
  • To make a stripe of RAIDZ2 vdevs (similar to RAID 60 on a hardware controller), add another four drives to extend the four-drive RAIDZ2.
  • To make a hot spare for a vdev, add a disk to the pool using Hot Spare.

The Add Vdevs button opens the Pool Manager in the Add Vdevs to Pool screen.

You cannot change the original encryption or data Vdev configuration.
TrueNAS selects data vdevs by default. To add different Vdev types to a pool, select one from the Add Vdev dropdown.

Using Scrub Pool

Use Scrub Pool to start a pool data integrity check.


If TrueNAS detects problems during the scrub operation, it either corrects them or generates an alert in the web interface.

By default, TrueNAS automatically checks every pool on a reoccurring scrub schedule.

To check the state of the last scrub or disks in the pool, use Status.

Extending a Vdev

Click Status to open the Pool Status screen.


Use the more_vert to display the options for a selected vdev. Click Extend to display the Extend Vdev dialog.

Select the disk from the dropdown list and click Extend.

Managing Pool Disks

The Pool Status screen disks also have disk management options.

See Replacing Disks for more information on the Offline, Replace and Online options.

Expand Pool

Click Expand Pool to increase the pool size to match all available disk space. An example is expanding a pool when resizing virtual disks apart from TrueNAS.

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