Cluster

1. When referring to a hard disk drive, a cluster or file allocation unit is the smallest managed section of a hard disk drive that holds a file. The size of a hard disk drive cluster can vary by operating system and size of hard disk drive.

Because each file and even directories take up one or more clusters depending on their size, earlier types of FAT potentially wasted hard disk drive space. For example, if the cluster size was 8k and a 2k file is stored on the computer, 6k of that cluster will go to waste.

This issue has been reduced with new versions of FAT have been made available such as FAT32 that help resolve this issue. Additional information about FAT32 can be found on our FAT32 page.

2. A cluster may also be used to define a group of computers and/or servers that share the work as one. Making one big computer instead of multiple smaller computers. To the right is an example of cluster of rack mountable computers at the NCSA/University of Illinois.

Also see: Beowulf, FAT, HACMP, Hard disk drive definitions, Lost cluster, MPP, MSCS, Network definitions, Server farm, SMP