Volume (computing)

In computer data storage, a volume or logical drive is a distinctly-addressable storage area with a single file system.

Storage can be designed and configured in many different and complex ways yet all include the volume concept. A general-purpose mass-storage device is typically divided into partitions with each partition used as a volume with its own file system. A more specialized mass-storage device may be configured for redundancy where a volume spans multiple storage media or physical drives. A smaller storage such as a memory card or floppy disk might have only one partition or no partition at all (no partition table) such that the volume is logically indistinguishable from the drive. A simple volume describes the most basic configuration: a volume on one storage medium with no redundancy or striping.

The following table describes an example storage configuration for a Windows system with two physical drives where the first drive has two partitions, and the second has only one. Each partition is treated as a volume with its own file system. The drive letters C:, D:, and E: each identify a volume, a.k.a. logical drive.

An operating system (OS) can potentially recognize a partition without recognizing a volume associated with it, as when a partition has not been formatted for a file system or is using a file system that the OS does not support. This occurs, for example, when Windows encounters a non-native partition, such as the ext4 filesystem commonly used with Linux.

A volume can be packed in a single file. Examples include the ISO9660 disc image (CD/DVD image, commonly called "ISO"), and the installer volume for Mac OS X (Apple Disk Image). As these volumes are files in a host volume, they are not partitions.

The concept of volume applies to any type of storage medium. But, for historical reasons, the term disk is often used even for non-disk media. For example, the Windows Disk Management utility supports any type of medium.