lvm

Logical Volume Manager (LVM) is a Linux storage management framework that provides a flexible layer of indirection between physical disks and filesystems. It pools multiple physical volumes into one or more volume groups, from which logical volumes are allocated. Logical volumes act as virtual disks that can be formatted with a filesystem or used directly by applications. The implementation commonly used in Linux is LVM2, which sits on top of the device-mapper kernel subsystem.

The core components are physical volumes, volume groups, and logical volumes. Physical volumes are disks or partitions prepared for LVM. A volume group combines one or more PVs into a storage pool. Logical volumes are carved from a volume group and serve as the actual storage units for filesystems or block devices. LVM supports metadata stored on the PVs to map logical extents to physical extents, enabling features such as resizing and mirroring.

Key features include online resizing of logical volumes, extending volume groups by adding new PVs, data movement between PVs without downtime, and snapshotting for backups. LVM also supports different layout options, such as linear, striped, and mirrored volumes, and, in LVM2, thin provisioning through thin pools for efficient space usage.

Typical usage involves creating PVs on disks, forming a VG, and then creating LVs for filesystems. Administration tools provide commands to display status, extend or reduce LVs, move data, and manage snapshots, making LVM a widely used solution for scalable and flexible Linux storage management.