zpools

Zpools are the top-level storage construct used by the ZFS filesystem. A zpool pools together one or more physical or virtual devices into a single storage pool that provides redundancy, performance, and data integrity. The pool is composed of one or more vdevs (virtual devices). Each vdev is a group of disks (or partitions) and determines the pool’s resiliency and performance. Vdevs can be configured as striped arrays (no redundancy), mirrors (two or more copies), or RAID-Z configurations (RAID-Z1, RAID-Z2, RAID-Z3). The overall pool capacity is the sum of the capacities of its vdevs, minus metadata and parity overhead; expansion is achieved by adding devices or new vdevs, or by replacing devices with larger ones.

Zpools provide data integrity through a copy-on-write transactional model and per-block checksums. Data and metadata are stored with end-to-end checksums so corrupted data can be detected and repaired using healthy copies if available. Within a pool, users create datasets (file systems) and zvols (block devices) to organize and consume storage. Features such as compression, optional deduplication, and advanced snapshots and clones are available at the dataset level.

Management and maintenance are performed with the zpool command. Common operations include creating or importing pools, attaching or detaching devices, replacing failed devices, importing or exporting pools, and scrubbing to detect and correct errors. If a device fails, ZFS can resilver the data onto remaining devices. Pools can be online, degraded, offline, or faulted, with health influenced by vdev topology and drive reliability.

The concept of zpools is central to ZFS, enabling scalable, resilient storage with integrated data protection and flexible provisioning.