Magnetic disk Physical characteristics - clusters

Cluster: one or more contiguous sectors.

Your disk is also divided into clusters or allocation units. Cluster size is dependent on the size of your hard disk drive - the larger the drive the larger the cluster.

FAT 32 was introduced in Win95B (OSR2) and Win98. Theoretically able to handle drives up to 140 terabytes (140,000 GB). Prior MS-DOS operating systems used FAT 16.

(If you use the MS-DOS command chkdsk these show up as allocation units)

	FAT 16
	Hard partition disk size 0-255MB 256-511MB 511-1023MB 1.023GB +	Cluster size 4KB 8KB 16KB 32KB
	FAT 32
	Hard partition disk size 512MB - 8GB 8GB - 16GB 16GB-32GB 32GB+	Cluster size 4KB 8KB 16KB 32KB

Only one file may be stored in each cluster - resulting in heaps of wasted space if you have lots of small files.
Ref: Livingston,B. (1996, Nov)

Disk compression

This cluster waste may be overcome using disk compression software. Generally the software will create one file taking the entire disk, then store the files using its own storage system - thereby avoiding the cluster problem.
Examples include Drivespace (DOS 6.2 and above, Win 95) and Stacker. (Wright 1996, Jul)