Zpool

A zpool is the storage pool used by the ZFS file system. It aggregates one or more physical storage devices into a single logical pool from which ZFS can create datasets and volumes. A pool is made up of one or more vdevs (virtual devices). A vdev is a group of physical devices arranged to provide redundancy and performance, typically as a mirror, RAID-Z1, RAID-Z2, or RAID-Z3 configuration. A pool's redundancy and capacity are determined by the layouts of its vdevs; a pool is healthy when all vdevs are ONLINE, and performance and capacity are driven by the sum of its disks minus parity overhead.

ZFS uses copy-on-write and end-to-end checksums, allowing self-healing across mirrors and RAIDs. If a device in a vdev fails but the pool has enough redundancy, data can be recovered automatically during reads. If all devices in a vdev fail or a vdev becomes unavailable, the pool can become DEGRADED or UNAVAILABLE.

Pools can be extended by adding new devices or by replacing existing disks, with resilvering rebuilding data on replacement devices. Administrators can further optimize performance with optional cache devices (L2ARC) and log devices (SLOG).

Management is performed with the zpool command, including creating pools (zpool create), listing status (zpool status), performing scrubs (zpool scrub), exporting/importing pools (zpool export/import), and destroying pools (zpool destroy). Zpool concepts are central to ZFS storage management and data integrity.