Storage media

There is no standard size, it depends on the media.

Drives are divided into Cylinders, Heads and Sectors, and these are finite numbers (pointers, if you like)and do not describe the size of the sector, just how many there are. The size of a sector depends on the type, capacity and format of the media.

For example, an Amiga Floppy disk has 80 Tracks (equivalent to cyclinders), 2 heads and 11 sectors per track. Each sector holds 512 bytes of data (cluster size).

On a typical hard disk, the CHS values point to a data area on the disk known as a cluster. The cluster is the smallest uniquely addressable division of a disk, and depending on the cluster size can hold varying amounts of data. This means that even if you only write one byte to a cluster, the full size of the cluster is allocated to that data, so on a hard disk with 4k byte clusters, a 100byte notepad document still takes up 4k, even if the file size is only 100 bytes. With Fat16 (16 bit CHS), the cluster size increased vastly as disks began to exceed 800mb so Fat32 using a 32 bit value for CHS was introduced to reduce cluster sizes and hence cluster waste.

Cluster waste...? If you save ten 1k files it will take 10 clusters. If the cluster size is 1k, the wasteis nil, or 0%. If you have a 4k cluster size, the waste is 75%. If you save a 5 k file on a 4k cluster drive, the waste is 37.5% (one whole cluster plus 75% wasted in the second cluster)

The smaller the cluster size, the more efficient the storage medium.