extent

1. [File System] A set of consecutively addressed blocks that is allocated to a single file.

2. [Storage System]

A set of consecutively located tracks on a CKD disk that is allocated to a single file.

3. [Storage System]

A set of consecutively addressed blocks that is part of a single virtual disk. A single storage device may be organized into multiple extents of different sizes, and may have multiple (possibly) non-adjacent extents that are part of the same virtual disk-to-member disk array mapping.

This type of extent is sometimes called a logical disk.