Datasets

The Datasets screen and widgets show information about datasets, provide access to data management functions, indicate the dataset roles, list the services using the dataset, show the encryption status, and list the permissions the dataset has in place. The screen focuses on managing data storage including user and group quotas, snapshots, and other data protection measures.

The Datasets screen shows No Datasets with a Create Pool button in the center of the screen until you add a pool and the first root dataset.

The screen has two main sections, the dataset tree table on the left and the Details for datasetname on the right. After creating a dataset, the tree table lists parent and child datasets (or zvols) on the system. The Details for datasetname area shows a set of dataset widgets for the selected or active row.

Large petabyte systems might report storage numbers inaccurately. Storage configurations with more than 9,007,199,254,740,992 bytes round the last 4 digits. For example, a system with 18,446,744,073,709,551,615 bytes reports the number as 18,446,744,073,709,552,000 bytes.

Add Zvol opens the Add Zvol screen.

Add Dataset opens the Add Dataset screen.

Begin typing the name of a dataset in the Search field to filter datasets to a short list of those matching what is typed.

The datasets tree table lists datasets in an expandable hierarchical structure with the root dataset first, then each child or non-root parent dataset, and the child datasets of each nested under them.

Click on any parent dataset to expand the tree table and show nested child datasets. Select a dataset to display the dataset widgets for that dataset.

The table of datasets includes used and available storage space for the dataset, encryption status (locked, unlocked, or unencrypted), the dataset role, and services that use it (e.g., the system dataset, a share, virtual machine, or application). Datasets and zvols have different icons. The icon represents zvols. The icon represents a dataset.

Tree Table Encryption Icons

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.

Tree Table Role Icons

Dataset tree table roles are represented by icons. Hover over the icons to view the description or icon label. Roles in the dataset tree correspond to the Roles widget. A dataset with an active task includes an activity spinner when that task is in progress.

Role	Icon	Description
System dataset		Indicates the parent (root) dataset designated as the system dataset. To change the system dataset go to System > Advanced Settings and edit the System Dataset Pool on the Storage widget.
Share		Indicates the dataset is used by a share or that child datasets of the parent are used by a share.
SMB share		Indicates the dataset is used by an SMB share.
VM		Indicates the dataset is used by a virtual machine (VM).
Apps		Indicates this dataset is used by an application and stores configuration and container-related data.

Each dataset has a set of information cards (widgets) that show in the Details for datasetname area of the screen. These widgets provide information grouped by functional areas. The set of widgets for a root or parent dataset differs from child datasets or datasets used by another service or with encryption.

Dataset widgets are:

• Dataset Details
• Dataset Space Management
• Data Protection
• Permissions
• Roles
• ZFS Encryption

The Dataset Details widget lists information on dataset type, sync type, compression, case sensitivity, Atime, and ZFS deduplication settings. Path shows the full path for the selected dataset.

A root dataset path shows the pool name alone.

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A child dataset path shows the root dataset (pool) name and parent dataset.

Edit opens the Edit Dataset screen for the selected dataset.

Promote appears on the Dataset Details widget when you select a cloned snapshot on the dataset tree table. This option promotes the cloned child dataset and allows users to delete the parent volume that created the clone. Otherwise, you cannot delete a clone while the original volume still exists. See zfs-promote.8.

Non-root parent and child dataset versions of the widget show the Delete button. Use the Disconnect/Export option on the Storage Dashboard screen to deleate a root datset.

Delete opens a window with information about other options or services using the dataset, for example, a parent to other datasets and the services the child datasets of a parent dataset uses. Non-root parent and child datasets include the Delete button.

The Delete window for a parent dataset (non-root) includes information about snapshots, shares, or other services such as apps or VMs that use the dataset. If a parent to other datasets, the window includes the services a child dataset uses.

If a child dataset uses services, the window shows the services.

If a service does not use a child dataset, the Delete window does not show a service.

The window includes a field to enter the path for the dataset. Enter the path and select Confirm to activate the Delete Dataset button.

The Dataset Space Management widget shows space allocation (reserved, used, available) for all datasets. The widget shows if an encrypted dataset is unlocked. After locking the dataset this widget disappears until you unlock the dataset.

The donut graph on the widget provides at-a-glance information and numeric values for the space allocated and used in the selected dataset. This includes data written and space allocated to child datasets of this dataset. It provides access to quota configuration options for the parent dataset and the child dataset of the parent and for users and groups with access to the dataset.

Edit opens the Capacity Settings screen where you can set quotas for the dataset.

Manage User Quotas screen and Manage Group Quotas opens the Manage Group Quotas screen.

The Data Protection widget shows for all datasets. It shows the number of snapshots and other data protection-related scheduled tasks (replication, cloud sync, rsync, and snapshots) configured on the system.

The Permissions widget shows the type of ACL as either NFSv4 or Unix Permissions (POSIX), lists access control user or group entries, and the owner and group for the dataset.

Root datasets have POSIX permissions and the entries are not editable. The permission screen and widget options vary based on the ACL type.

Parent and child dataset permissions (NFSv4 or POSIX) are editable.

NFSv4 ACL type (the default ACL type) shows the user and group entries on the Permissions widget as buttons. Click to show a selectable checklist of Permissions Advanced and Flags Advanced options for that entry on the Permissions widget.

A dataset with a POSIX ACL type is only editable using the Edit button.

Edit opens the Edit ACL for ACL type.

The Roles widget shows the dataset role or the service that uses it (i.e., a share, application, virtual machine, or it being the system dataset). A parent dataset shows information on child datasets that a service uses. If the dataset is also the system dataset, the widget includes a link to the System > Advanced Settings screen where you can manage the system dataset on the Storage widget.

The ZFS Encryption widget only shows for datasets configured with encryption. Options shown in the widget vary based on the type of dataset (root, non-root parent, or child dataset). It includes the current state of the dataset encryption, the encryption root, the type, and the algorithm used.

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The ZFS Encryption widget shows the Lock or Unlock options. These are not available on the widget for the root dataset or a child dataset of a non-root parent inheriting encryption settings from the parent. The root dataset ZFS Encryption widget includes the Export All Keys and the Export Key options, and the Edit option to change encryption settings. Parent or child dataset ZFS Encryption widgets include the options to Lock and Unlock the dataset, and to Edit the encryption settings.

Child dataset ZFS Encryption widgets include the Go to Encryption Root when the Encryption Options setting is set to Inherit. The non-root parent dataset controls the state of the child dataset.

Edit opens the Edit Encryption Options for dataset window for the selected dataset.

For more details on encryption windows and functions see Encryption Settings.

The Add Dataset and Edit Dataset screens allow admin users with the right permission level to create and or modify datasets. Both screens include the same settings but you cannot change the dataset name, Dataset Preset selection, or the Case Sensitivity settings on the Advanced Options screen after clicking Save on the Add Dataset screen.

After adding a dataset, Edit on the Dataset Details widget opens the Edit Dataset screen. Edit on the ZFS Encryption widget, opens a encryption edit screen. The ZFS Encryption widget only shows if the dataset uses encryption. Edit on the Permissions widget opens the Edit ACL screen to edit dataset permissions.

Add Dataset and Edit Dataset screens include the Basic Options and Advanced Options. TheBasic Options and Advanced Options screens include the Name and Options section.

The Advanced Options screen shows:

• Quota management tools and settings
• Encryption Options settings
• Other Options settings

The Basic Options and Advanced Options screens show the Name and Options settings section. The common settings are Parent Path, Name, and the Dataset Preset (previously known as the share type).

Only shows on the Advanced Options screen. The This Dataset and This Dataset and Child Datasets sections include the same setting options. This Dataset applies the quota settings to the dataset being created or edited. This Dataset and Child Datasets applies quota settings to any children of the dataset. These settings also display on the Capacity Settings screen.

Setting a quota defines the maximum allowed space for the dataset or the dataset and child datasets. You can reserve a defined amount of pool space to prevent automatically-generated data like system logs from consuming all available dataset space. You can configure quotas for only the new dataset or include all child datasets in the quota.

Encryption setting options display on the Advanced Options of the Add Dataset screen but not on the Edit Dataset screen. To edit encryption settings, click Edit on the ZFS Encryption widget. This opens the Edit Encryption Options for datasetName window where you can change encryption settings for an existing dataset.

If you create an unencrypted dataset, the default setting is Inherit (Non-Encrypted), and you can create encrypted or unencrypted child datasets under it. If you create an encrypted dataset, the default setting is Inherit (Encryption), and all child datasets created under it are encrypted. The default Inherit option is pre-selected.

Clear the Encryption option (pre-selected) checkbox to show the key type encryption settings. Select Passphrase in Encryption Type to show other settings.

The Other Options tune the dataset for specific data-sharing protocols by setting compression level and sync type options, ACL type and mode, and other settings.

Other Options Settings

Setting	Description
Comment	Optional text entered to describe or define the dataset usage or any other information to associate with the dataset.
Sync	Sets the sync setting to the selected option on the dropdown list. Options are: Standard uses the sync settings requested by the client software. Always waits for data writes to complete. Disabled never waits for writes to complete.
Compression level	Sets the compression algorithm to apply to the option selected on the dropdown list. Options encode information in less space than the original data occupies. We recommend choosing a compression algorithm that balances disk performance against the amount of space saved. Options include: LZ4 is generally recommended as it maximizes performance and dynamically identifies the best files to compress. ZSTD is the Zstandard compression algorithm with several options for balancing speed and compression. Gzip options range from 1 for least compression with best performance or 9 for maximum compression with greatest performance impact. ZLE is a fast algorithm that only eliminates runs of zeroes. LZJB is a legacy algorithm that is not recommended for use.
Enable Atime	Sets the access time for files to the selected option on the dropdown list. Access time can result in significant performance gains. Inherit uses the access time setting of the parent or the root dataset. On updates the access time for files when they are read. Off disables creating log traffic when reading files to maximize performance.
ZFS Deduplication	Sets the option to transparently reuse a single copy of duplicated data to save space to the option selected on the dropdown list. Options are: Inherit - Select to use the parent or root dataset settings. On - Select to use deduplication. Off - Select to not use deduplication. Verify - Select to do a byte-to-byte comparison when two blocks have the same signature to verify the block contents are identical. Deduplication can improve storage capacity but is RAM intensive. Compressing data is recommended before using deduplication. Deduplicating data is a one-way process. You cannot undo deduplicated data!
Case Sensitivity	Sets case sensitivity to the option selected on the dropdown list. Options are: Sensitive assumes file names are case sensitive. Insensitive assumes file names are not case sensitive. You cannot change case sensitivity after saving the dataset. Note: The Mixed option no longer exists.
Checksum	Sets the checksum to the option selected on the dropdown list. Options: Inherit - Select to use the parent setting. On - Select to use checksum without specifying the variant. FLETCHER2 (deprecated) or FLETCHER4 - Select to use a position-dependent checksum that uses two checksums to determine single-bit errors in messages transmitted over network channels or ZFS streams. SHA256 (default for deduped datasets) or SHA512 - Select to use a sequence of numbers and letters to check the copy of a downloaded update file is identical to the original. SKEIN Not supported for a file system on boot pools. EDNOR is not supported for file systems on boot pools and Edon-R requires verification when used with dedup so it automatically uses verify.

Setting	Description
Read-only	Sets the option that allows or prevents dataset modification to the option selected on the dropdown list. On prevents modifying the dataset. Off allows users accessing the dataset to modify its contents.
Exec	Sets the option for executing processes from within the dataset to the option selected on the dropdown list. On allows executing processes from within this dataset. Off prevents executing processes from within the dataset. We recommend setting it to On.
Snapshot directory	Sets the option that controls visibility of the .zfs directory on the dataset from the option selected on dropdown list. Select Visible, Invisible, or Disabled.
Snapdev	Sets the option that controls whether the volume snapshot devices under /dev/zvol/poolname are hidden or visible to the options selected on the dropdown list. Options are Inherit (hidden), Visible and Hidden (default value).
Copies	Sets the number of ZFS user data duplicates stored on this dataset to the option selected on the dropdown list. Select between 1, 2, or 3 redundant data copies. This can improve data protection and retention but is not a substitute for storage pools with disk redundancy.
Record Size	Sets the logical block size in the dataset to the option selected on the dropdown list. Matching the fixed size of data, as in a database, can result in better performance.
ACL Type	Sets the access control list type to the option selected on the dropdown list. Options are: Inherit - Select to preserve ACL type from the parent dataset. Off - Select to use neither NFSv4 or POSIX protocols. NFSv4 -Select to cleanly migrate Windows-style ACLs across Active Directory domains (or stand-alone servers) that use ACL models richer than POSIX. Since POSIX ACLs are a Linux-specific ZFS feature, administrators should use NFSv4 to maintain compatibility with TrueNAS Core, FreeBSD, or other non-Linux ZFS implementations. POSIX - Select when an organization data backup target does not support native NFSv4 ACLs. Since the Linux platform used POSIX for a long time, many backup products that access the server outside the SMB protocol cannot understand or preserve native NFSv4 ACLs. All datasets within an SMB share path must have identical ACL types. For a more in-depth explanation of ACLs and configurations in TrueNAS, see our ACL Primer. This advanced setting changes ACL type and mode settings configured by the Dataset Preset option. Do not make changes here if you do not understand ACLs.
ACL Mode	Sets the option that determines how chmod behaves when adjusting file ACLs to the option selected on the dropdown list. See the zfs(8) aclmode property for more information. Options are: Passthrough - Only updates ACL entries related to the file or directory mode. Restricted - Does not allow chmod to make changes to files or directories with a non-trivial ACL. An ACL is trivial if it can be fully expressed as a file mode without losing access rules. Set ACL Mode to restricted to optimize a dataset for SMB sharing, but it can also require further optimizations. For example, configuring an rsync task with this dataset could require adding --no-perms in the task Auxiliary Parameters field.
Metadata (Special) Small Block Size	Sets a threshold block size for small file blocks you include in the special allocation class (fusion pools) to the entered value. Blocks smaller than or equal to this value are assigned to the special allocation class while greater blocks are assigned to the regular class. Valid values are zero or a power of two from 512B up to 1M. The default size 0 means no small file blocks are allocated in the special class. Before setting this property, you must add a metadata special class VDEV to the pool.