Disc Clusters
A cluster is the minimum unit of file space on a hard disk or disk partition; also known as an 'allocation unit'. If the cluster size is 16KB, then a 1 KB file and a 7 KB file will each take 16KB of actual disk space; a 17KB file will take 32KB. Clearly smaller clusters make more efficient use of hard drive space, however there can be a small trade off in performance terms due to increased fragmentation. Audio discs with large files will benefit from the largest cluster size that the file system allows for.

The table below shows the cluster sizes that are set automatically by XP when formatting hard discs. As you will notice, it is the volume size that determines this.

FAT32 CLUSTER SIZE

CLUSTER SIZE MIN. PARTITION SIZE MAX. PARTITION SIZE
4 KB 0.5 GB 8 GB
8 KB 8 GB 16 GB
16 KB 16 GB 32 GB
32 KB 32 GB 64 GB

NTFS CLUSTER SIZE

CLUSTER SIZE MIN. PARTITION SIZE MAX. PARTITION SIZE
0.5 KB 0 GB 0.5 GB
1 KB 0.5 GB 1 GB
2 KB 1 GB 2 GB
4 KB 2 GB 4 GB
8 KB 4 GB 8 GB
16 KB 8 GB 16 GB
32 KB 16 GB 32 GB
64 KB 32 GB 64 GB