Datasets

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

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

After creating a dataset, the screen shows the dataset tree table on the left and the Details for datasetname dataset widgets on the right. The tree table with multiple datasets lists parent and child datasets (or zvols) on the system. Icons representing the storage type or a service, such as SMB share or the system dataset, show at the right of a row.

Large petabyte systems might report storage numbers inaccurately. Storage configurations with more than 9,007,199,254,740,992 bytes round to 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 shows an expandable hierarchical structure, starting with the root dataset, then each non-parent or parent and child datasets, with the child datasets nested under each parent dataset.

The top row of the tree table is selected by default when you go to the Datasets screen. The widgets on the right show information for the selected dataset.

Click on any parent dataset to expand the tree table to show nested child datasets.

The table of datasets shows used and available storage space for each dataset, encryption status (locked, unlocked, or unencrypted), and dataset usage, such as the services using 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 Usage Icons

The dataset tree table shows icons representing the service type. Hover over the icons to view the description or icon label. Usage in the dataset tree corresponds to the Usage widget. A dataset with an active task includes an activity spinner when that task is in progress.

Usage	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) in the Details for datasetname area of the screen. These widgets and information is grouped by functional areas. The widgets for a root or parent dataset differ from a child dataset, or a dataset used by another service or with encryption.

Dataset widgets are:

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

The Details widget shows information about the dataset that allows you to manage an existing dataset.

Information includes:

• Sync - Shows the type of dataset. For example, STANDARD for non-root datasets or ROOT DATASET for the first pool or root dataset, which is usually the system dataset.
• Compression - Shows the compression algorithm applied to the dataset. See Data Compression Algorithms for more information.
• Enable Atime - Shows if this is on or off. See Advanced Options for more information.
• ZFS Deduplication - Shows if ZFS deduplication is on or off. See Advanced Options for more information.
• Case Sensitivity - Shows if case sensitivity is on or off. See Advanced Options for more information.
• Path - Shows the mount path to the dataset.

A root dataset path shows the pool name alone. If there are multiple pools on the system, the first pool created is the system dataset. The root dataset for a pool is the top-level container in your pool, sharing the same name as the pool itself. When managing your TrueNAS system, it is generally best practice to create dedicated datasets under the root dataset for different types of data, rather than storing data directly in the root dataset itself.

Edit opens the Edit Dataset screen for the selected dataset.

Delete shows on the Details widget for non-root datasets. Use the Disconnect/Export option on the Storage Dashboard screen to deleate a root dataset.

Delete opens a Delete dataset window with information about other options or services using the dataset, for example, a parent to other datasets, the services child datasets of a parent dataset uses, shares like SMB and/or NFS, or a multiprotocol share, and the path to the datasets the shares use.

Promote shows on the Details widget for a dataset created by cloning a snapshot on the dataset tree table. It 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.

The Delete window shows information about the dataset, including the path, services that depend on the dataset, and shares using the dataset and the path to the dataset.

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

The window includes a field where you enter the path to the dataset. Confirm activate the Delete Dataset button. Delete Dataset deletes the dataset and all data it contains.

The Space Management widget shows the total space allocation (data written, children of the dataset, available space). 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 shows the available space in the dataset.

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

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

The Data Protection widget shows snapshot and backup task information for the dataset.

Take Snapshot opens the Add Snapshot screen.

View Snapshot Tasks opens the Data Protection screen where you can add or manage scheduled periodic snapshot tasks.

No Backup Tasks shows when no data protection backup tasks are created. Go to Backups opens the Data Protection > Replications Tasks screen list view, where you can manage scheduled replication tasks.

The Permissions widget shows the type of ACL permissions applied to the dataset. ACL types can be NFSv4 or Unix Permissions (POSIX), and each lists access control user or group entries, and the owner and group for the dataset.

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

Non-root dataset can be POSIX or NFSv4 based on the Dataset Preset selected when you create the dataset.

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

Edit for a POSIX ACL opens the Unix Permissions Editor screen. Root datasets do not show the Edit button.

Edit for an NFSv4 ACL opens the Edit ACL screen.

The Usage widget shows the dataset role or services that use it (i.e., a share, application, virtual machine, or the system dataset). It shows an icon for and information about the service using the dataset. A corresponding icon shows on the row for the dataset in the dataset tree table.

The Manage Advanced Settings shows for the system dataset, and opens the Advanced Settings screen. If the dataset is associated with a share, a Manage SMB Share link shows. where SMB is the share type and opens the corresponding share screen.

It shows Not Shared if the dataset is configured with a share preset like SMB but does not have a share created. The Usage widget shows two links: Create SMB Share that opens the Add SMB screen and Create NFS Share that opens the Add NFS screen.

The Usage widget for a parent dataset with child datasets with shares shows this, but does not link to other screens.

The Encryption widget only shows for encrypted datasets. 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, and the type.

The Encryption widget shows Lock when the dataset is unlocked or Unlock when the dataset is locked. These are not available on the widget for the root dataset.

The Encryption widget shows Export Key when the encryption type is set to key. Export Key downloads the system-generated encryption key to a JSON file. You can find this in your Windows Downloads folder.

Edit opens the Edit Encryption Options for datasetname window. A root dataset does not include the Edit button. We do not recommend encrypting the root or system dataset!

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

The Add Dataset and Edit Dataset screens allow admin users with full control access to create and manage datasets. Both screens include the same Advanced Options 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.

Edit on the Dataset Details widget opens the Edit Dataset screen.

Edit on the Encryption widget opens an encryption edit window. The Encryption widget only shows if a dataset is encrypted. Edit on the Permissions widget opens the Edit ACL screen to edit dataset NFSv4 permissions. POSIX ACLs open the Unix Permissions Editor screen.

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

The Advanced Options screen shows:

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

The Basic Options show on the Advanced Options screen.

The Add Dataset and Edit Dataset screens show the Advanced Options button. Advanced Options show:

• Quota Management settings
• **Encryption settings
• Other Options settings

Setting a quota defines the maximum allowed space for the dataset or the dataset and its 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.

Quota management settings on the Advanced Options screen set quotas for the selected dataset, and can set the quota for the child datasets of the selected dataset. The Edit button on the dataset Space Management widget opens the Capacity Setting Options for user or group levels can be accessed from the Storage Dashboard screen.

The quota management settings options:

• This Dataset - Sets quotas for only the selected dataset.
• This Dataset and Child Datasets - Sets quotas for the child datasets of the selected dataset.

These settings also display on the Capacity Settings screen that sets quotas at the pool level.

Encryption settings apply key or passphrase type encryption to the selected dataset, and encrypt any child datasets of an encrypted parent. Encryption settings show on in the Advanced Options screen for the Add Dataset screen, but not on the Edit Dataset screen. Edit on the Encryption widget opens the Edit Encryption Options for datasetName window, showing the current encryption settings for the selected dataset and allowing you to change the encryption type settings.

Inherit (Non-Encrypted) shows when you create an unencrypted dataset. Inherit (Encryption) shows when you create an encrypted dataset. All child datasets created under an encrypted dataset are encrypted.

The Encryption option (pre-selected), when selected, shows the key type encryption settings by default. Passphrase in Encryption Type to show other settings.

The Other Options section tunes the dataset for specific data-sharing protocols, sets compression level, sync type options, ACL type and mode, and other settings.

Other Options Settings

Setting	Description
Comment	Text entry field for optional text to describe or define the dataset usage or any other information to associate with the dataset.
Sync	Sets the sync type to the option selected 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	Applies the compression algorithm 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 - Generally recommended as it maximizes performance and dynamically identifies the best files to compress. ZSTD - Uses the Zstandard compression algorithm. Has several options for balancing speed and compression. Gzip - Has options that range from 1 for least compression with best performance or 9 for maximum compression with greatest performance impact. ZLE - Has a fast algorithm that only eliminates runs of zeroes. LZJB - 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: Inherit - Uses the parent or root dataset settings. On - Uses deduplication. Off - Does not use deduplication. Verify - Use 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 - Uses the parent setting. On - Uses the checksum without specifying the variant. FLETCHER2 (deprecated) or FLETCHER4 - Uses 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 - Uses 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 - 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 to access 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 in the 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: Inherit - Preserves ACL type from the parent dataset. Off - Uses neither NFSv4 nor POSIX protocols. NFSv4 - 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, FreeBSD, or other non-Linux ZFS implementations. POSIX - Use when a data backup target does not support native NFSv4 ACLs. Since the Linux platform has 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	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: 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.