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Pool Screens

  8 minute read.

Last Modified 2022-07-29 16:33 EDT

The Storage screen displays a list of all the pools and datasets or zvols configured in your TrueNAS.

Pool Manager Screen

To access the Pool Manager screen to create a new pool click Create Pool. To access Pool Manager to modify an existing pool, click the icon button for the pool and select Add Vdevs.


If your system disks do not have unique serial numbers, the Pool Manager screen displays a warning message and the Show disks with non-unique serial numbers option.


Select Show disks with non-unique serial numbers to display the system disks. The 0 selected/ # total below the Available Disks displays a count of the number of disks selected to the total number of disks available on your system. This counter keeps track of the total number of available disk in the system when disks span across several screen pages.

NameEnter the name you want to use for the pool. Choose something that helps you identify this pool and the type of data it stores. This helps with locating data in systems with pages or hundreds of storage pools configured on the system.
EncryptionSelect to enable encryption for this pool, the root dataset and if desired, child datasets and zvols in this pool. See Storage Encryption for more information on using SCALE storage encryption.
Reset LayoutClick to clear a suggested layout after you click Suggest Layout.
Suggested LayoutClick to have TrueNAS review all available disks and populate the primary Data VDev list with identically-sized drives in a configuration balanced between storage capacity and data redundancy. Reset Layout clears the suggested layout.
Add VdevClick to display the dropdown list of vdev options in the section below.
Available DisksDisplays the list of disks on your system. Click the chevron_right expand icon to see the disk serial number and model number and where it is on the Enclosure screen (the position in the server if using iXsystems-provided hardware).
Data VDevsDefault vdev type on the Pool Manager screen. After selecting a vdev type from the Add Vdev a new list displays under the Data VDevs list.
RepeatClick to create another vdev of the same type and configuration below the exiting Data VDevs list.
Vdev typeThe vdev type dropdown list below the Data Vdevs list displays Stripe but then changes to Mirror after you select two disks and move them to the Data Vdevs list. If you select more than two disk you can select different types from this list based on the number of disks moved.
Estimated raw capacityDisplays the raw storage capacity of the disks for the Data VDev type. For a mirror, this is the storage of one disk with the other disk provides redundancy.
Estimated total raw data capacity
Estimated data capacity available after extension
The total estimated raw capacity of the disks in the vdev. Estimated total raw data capacity changes to Estimated data capacity available after extension on the Add Vdevs to Pool version of Pool Manager.

Vdev Layout Options

DataData is the standard vdev for primary storage operations. Each storage pool requires at least one Data vdev. Data vdev configuration typically affects how users can configure other types of vdevs.
CacheA cache vdevs is a ZFS L2ARC read-cache used with fast devices to accelerate read operations. Users can add or remove cache vdevs after creating the pool.
LogA log vdev is a ZFS LOG device that improves synchronous write speeds. Users can add or remove log vdevs after creating the pool.
Hot SpareA Hot Spare vdev is a drive or drives reserved for inserting into data vdevs when an active drive fails. The system uses hot spares as temporary replacements for failed drives to prevent larger pool and data loss scenarios. When a user replaces a failed drive with a new one, the hot spare reverts to an inactive state and becomes available again as a hot spare. If a user detaches the failed drive from the pool without adding a new one, the system promotes the temporary hot spare to a full data vdev member.
MetadataA metadata vdev is a special allocation class used to create fusion pools for increased metadata and small block I/O performance.
DedupA dedup vdev stores ZFS de-duplication. Requires allocating X GiB for every X TiB of general storage. Example: 1 GiB of dedup vdev capacity for every 1 TiB of data vdev availability.

Vdev Options

StripeEach disk stores data. A Stripe requires at least one disk and has no data redundancy.
MirrorData is identical in each disk. A Mirror requires at least two disks, provides the most redundancy, and has the least capacity.
RAIDZ1Uses one disk for parity while all other disks store data. RAIDZ1 requires at least three disks.
RAIDZ2Uses two disks for parity while all other disks store data. RAIDZ2 requires at least four disks.
RAIDZ3Uses three disks for parity while all other disks store data. RAIDZ3 requires at least five disks.

Pool Actions List Options

The Pool Actions dropdown list displays options to expand the pool, check the status of disks in the pool, implement ZFS TRIM, perform an integrity check on the pool, and export or disconnect the pool. If the pool is configured to use encryption, the option to export dataset keys also displays on the Pool Actions dropdown list.

To access options for pools listed on the Storage screen click on the icon button to display the Pool Actions dropdown list of options.


Pool Options Dialog

Select Pool Options to display the Edit Pool Options dialog.


Select Auto TRIM to enable TrueNAS to periodically review data blocks to identify empty obsolete blocks it can delete. If left clear (default), TrueNAS incorporates day-block overwrites when a device write starts.

When enabled, TrueNAS to periodically reviews data blocks tp identify the blocks it can reclaim. Auto TRIM is disabled because it can impact pool performance.

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

Select Confirm to activate Save.

Export/Disconnect Window

Select Export/Disconnect to display the Export/disconnect pool: poolname window. Export/Disconnect allows users to export, disconnect, or delete a pool. Disks in the pool become available to use in a new pool. A warning displays stating data becomes unavailble after an export and that selecting Destroy Data on this pool destroys data on the pool disks.

This can be a destructive process! Back up all data before performing this operation. You might not be able to recover data lost though this operation.


If a share uses the pool this window displays the share type (for example, SMB share, etc.) affected by the export/disconnect operation.


Destroy data on this pool?Select to erase all data on the pool. When selected the Confirm Export/Disconnect checkbox disappears.
Delete configuration of shares that sued this pool?Enabled by default to remove the share connection to this pool. Exporting or disconnecting the pool deletes the configuration of shares using this pool. You must reconfigure the shares affected by this operation.
Confirm Export/DisconnectRequired option. Select to confirm this operation and accept the warnings displayed. Activates the Export/Disconnect button.

Click Export/Disconnect to execute the process and begin the pool export or disconnect. A status window displays with progress. When complete, a final dialog displays stating the export/disconnect completed successfully.

Add Vdevs Screen

Displays the Add Vdev to Pool screen with Pool Manager showing the selected pool. You cannot rename the pool or change the vdev type.


The screen settings are described in the Pool Manager section above.

Scrub Pool Dialog

Select Scrub Pool to display the start pool scrub dialog. Select Confirm to activate the Start Scrub button.


Scrub Pool initiates a check on pool data integrity. If TrueNAS detects any problems during the scrub, it either corrects them automatically or generates an alert in the web interface.

By default, TrueNAS automatically checks every pool to verify it is on a reoccurring scrub schedule.

Status Screen

Select Status to display the Pool Status screen that lists the pool, vdev type, and drives in the pool.


Pool Status screen displays the status of any scrub operation, errors encountered and the date of the scrub operation.

The list displays the number of reads, writes and checksums, and the status of each root dataset, vdev for the root dataset, and disks in the vdev.

Use Refresh to update the screen after making a change.

Click the more_vert for the pool vdev to display the vdev type actions dropdown list if the type is Mirror. Options are Extend or Remove.

Click the more_vert for a disk to display Disk Actions dropdown list. Options are Edit, Offline, Online, Replace, Remove and Detach. See Disk Screen for more information on these options.

Expand Pool

Select Expand Pool to increase the pool size to match all available disk space. Users with pools using virtual disks use this otpion to resize these virtual disks apart from TrueNAS.

Export Dataset Keys Dialog

Select Export Dataset Keys to obtain the encryption keys for the dataset. Displays the exported json file at the bottom of the screen. Click the expand icon and select the desired option for the downloaded file.

Keep exported encryption files in a safe and secure location!

Always back up encryption keys. Losing an encryption key could result in permanently locked, or lost, data!

Import Pool Screens

Click Import to view the Import Pool wizard screens.


Use the Pool Import Summary dropdown to select the pool to import. Click Next to advance to the Confirm Options screen


Click Import to begin the pool import process.

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