Managing Pools

The Storage Dashboard widgets provide access to pool management options to keep the pool and disks healthy, upgrade pools and VDEVs, open datasets, snapshots, data protection screens, and manage S.M.A.R.T. tests. This article provides instructions on pool management functions available in the SCALE UI.

Select Storage on the main navigation panel to open the Storage Dashboard. Locate the ZFS Health widget for the pool, then click the Edit Auto TRIM. The Pool Options for poolname dialog opens.

Select Auto TRIM.

Click 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.

Use the Export/Disconnect button to disconnect a pool and transfer drives to a new system where you can import the pool. It also lets you completely delete the pool and any data stored on it.

Click on Export/Disconnect on the Storage Dashboard.

A dialog displays showing any system services affected by exporting the pool, and options based on services configured on the system.

To delete the pool and erase all the data on the pool, select Destroy data on this pool. The pool name field displays at the bottom of the window. Type the pool name into this field. To export the pool, do not select this option.

Select Delete saved configurations from TrueNAS? to delete shares and saved configurations on this pool.

Select Confirm Export/Disconnect

Click Export/Disconnect. A confirmation dialog displays when the export/disconnect completes.

ZFS supports adding VDEVs to an existing ZFS pool to increase the capacity or performance of the pool.

You cannot change the original encryption or data VDEV configuration.

To add a VDEV to a pool: Click Manage Devices on the Topology widget to open the Devices screen. Click Add VDEV on the Devices screen to open the Add Vdevs to Pool screen.

Adding a vdev to an existing pool follows the same process as documented in Create Pool. Click on the type of vdev you want to add, for example, to add a spare, click on Spare to show the vdev spare options.

To use the automated option, select the disk size from the Automated Disk Selection > Disk Size dropdown list, then select the number of vdevs to add from the Width dropdown. To add the vdev manually, click Manual Disk Selection to open the Manual Selection screen.

Click Add to show the vdev options available for the vdev type. The example image shows adding a stripe vdev for the spare. Vdev options are limited by the number of available disks in your system and the configuration of any existing vdevs of that type in the pool. Drag the disk icon to the stripe vdev, then click Save Selection.

The Manual Selection screen closes and returns to the Add Vdev to Pool wizard screen (in this case the Spare option.)

You have the option to accept the change or click Edit Manual Disk Selection to change the disk added to the strip vdev for the spare, or click Reset Step to clear the strip vdev from the spare completely. Click either Next or a numbered item to add another type of vdev to this pool.

Repeat the same process above for each type of vdev to add.

Click Save and Go to Review to go to the Review screen when ready to save your changes.

To make changes, click either Back or the vdev option (i.e., Log, Cache, etc.) to return to the settings for that vdev. To clear all changes, click Start Over. Select Confirm then click Start Over to clear all changes.

To save changes click Update Pool.

You cannot add more drives to an existing data VDEV but you can stripe a new VDEV of the same type to increase the overall pool size.

To extend a pool, you must add a data VDEV of the same type as existing VDEVs. For example, create another mirror, then stripe the new mirror VDEV to the existing mirror VDEV. While on the Devices screen, click on the data vdev, then click Extend.

You can always remove the L2ARC (cache) and SLOG (log) VDEVs from an existing pool, regardless of topology or VDEV type. Removing these devices does not impact data integrity, but can significantly impact performance for reads and writes.

In addition, you can remove a data VDEV from an existing pool under specific circumstances. This process preserves data integrity but has multiple requirements:

• The pool must be upgraded to a ZFS version that includes the device_removal feature flag. The system shows the Upgrade button after upgrading SCALE when new ZFS feature flags are available.
• All top-level VDEVs in the pool must be only mirrors or stripes.
• Special VDEVs cannot be removed when RAIDZ data VDEVs are present.
• All top-level VDEVs in the pool must use the same basic allocation unit size (ashift).
• The remaining data VDEVs must contain sufficient free space to hold all of the data from the removed VDEV.

When a RAIDZ data VDEV is present, it is generally not possible to remove a device.

To remove a VDEV from a pool:

1. Click Manage Devices on the Topology widget to open the Devices screen.
2. Click the device or drive to remove, then click the Remove button in the ZFS Info pane. If the Remove button is not visible, check that all conditions for VDEV removal listed above are correct.
3. Confirm the removal operation and click the Remove button.

The VDEV removal process status shows in the Task Manager (or alternately with the zpool status command). Avoid physically removing or attempting to wipe the disks until the removal operation completes.

Use Scrub on the ZFS Health pool widget to start a pool data integrity check.

Click Scrub to open the Scrub Pool dialog. Select Confirm, then click Start Scrub.

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 recurring scrub schedule.

The ZFS Health widget displays the state of the last scrub or disks in the pool. To view scheduled scrub tasks, click View all Scrub Tasks on the ZFS Health widget.

The Storage Dashboard screen Disks button and the Manage Disks button on the Disk Health widget both open the Disks screen.

Manage Devices on the Topology widget opens the Devices screen. To manage disks in a pool, click on the VDEV to expand it and show the disks in that VDEV. Click on a disk to see the devices widgets for that disk. You can take a disk offline, detach it, replace it, manage the SED encryption password, and perform other disk management tasks from this screen.

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

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

Storage pool upgrades are typically not required unless the new OpenZFS feature flags are deemed necessary for required or improved system operation.

Do not do a pool-wide ZFS upgrade until you are ready to commit to this SCALE major version and lose the ability to roll back to an earlier major version!

The Upgrade button displays on the Storage Dashboard for existing pools after an upgrade to a new TrueNAS major version that includes new OpenZFS feature flags. Newly created pools are always up to date with the OpenZFS feature flags available in the installed TrueNAS version.

The upgrade itself only takes a few seconds and is non-disruptive. It is not necessary to stop any sharing services to upgrade the pool. However, the best practice is to upgrade when the pool is not in heavy use. The upgrade process suspends I/O for a short period but is nearly instantaneous on a quiet pool.