A ZFS Volume (zvol) is a dataset that represents a block device or virtual disk drive. TrueNAS requires a zvol when configuring iSCSI Shares. Adding a virtual machine also creates a zvol to use for storage.

To create a zvol, go to Datasets. Select the root or non-root parent dataset where you want to add the zvol, and then click Add Zvol.

The zvol screens and widgets, accessed from the Datasets screen, allow you to add or edit a zvol and manage the volume storage. Zvols are listed on the Datasets screen tree table.

The tree table includes storage space used and available for that zvol (or dataset), encryption status (locked, unlocked, or unencrypted), and the role of that zvol or dataset or what service uses it (i.e., the system dataset, a share, virtual machine, or application).

The Snapshots screen lists dataset snapshots on the system. It allows you to add new or manage existing snapshots.

Access to the Snapshots screen is available using the Manage Snapshots link on the Data Protection widget on the Datasets screen and by clicking Snapshots on the Periodic Snapshot Tasks widget on the Data Protection screen.

If the selected dataset does not have snapshots, the screen displays No Snapshots are Available.

Datasets, root, non-root parent, and child, or zvols with encryption include the ZFS Encryption widget in the set of dataset widgets displayed on the Datasets screen.

The Datasets tree table includes lock icons and descriptions that indicate the encryption state of datasets.

Icon	State	Description
	Locked	Displays for locked encrypted root, non-root parent and child datasets.
	Unlocked	Displays for unlocked encrypted root, non-root parent and child datasets.
	Locked by ancestor	Displays for locked datasets that inherit encryption properties from the parent.
	Unlocked by ancestor	Displays for unlocked datasets that inherit encryption properties from the parent.

The Encryption option on the Pool Manager screen sets encryption for the pool and root dataset.

TrueNAS offers ZFS encryption for your sensitive data in datasets and zvols.

Data-at-rest encryption is available with:

• Self Encrypting Drives (SEDs) using OPAL or FIPS 140.2 (Both AES 256)
• Encryption of specific datasets (AES-256-GCM)

The local TrueNAS system manages keys for data-at-rest. Users are responsible for storing and securing their keys. TrueNAS includes the Key Management Interface Protocol (KMIP).