TrueNAS uses ZFS data storage pools to efficiently store and protect data.

What is a pool? Storage pools are attached drives organized into virtual devices (vdevs). ZFS and TrueNAS periodically review and heal when discovering a bad block in a pool. Drives are arranged inside vdevs to provide varying amounts of redundancy and performance. Combined, ZFS and vdevs combined create high-performance pools, pools that maximize data lifetime, and all situations in between.

For more on ZFS storage, see ZFS Primer.

Review Storage Needs

We strongly recommend users review the available system resources and plan the storage use case before creating a storage pool.

  • Allocating more drives to a pool increases redundancy when storing critical information.
  • Maximizing total available storage at the expense of redundancy or performance entails allocating large-volume disks and configuring a pool for minimal redundancy.
  • Maximizing pool performance entails installing and allocating high-speed SSD drives to a pool.

Determining your specific storage requirements is a critical step before creating a pool.


  • Disks: Describes UI screens and dialogs related to disk operations.

    • Pool Creation Wizard: Descriptions for settings and functions found in the Pool Creation Wizard.

      • Devices Screens: Provides information on settings and functions found on the Devices screens and widget.