Specifies the disk allocation unit size or cluster size. All file systems used by this version of Windows organize your hard ...

Specifies the disk allocation unit size or cluster size. All file systems used by this version of Windows organize your hard disk based on cluster size, which represents the smallest amount of disk space that can be allocated to hold a file. The smaller the cluster size you use, the more efficiently your disk stores information. If no cluster size is specified during format, Windows picks defaults based on the size of the volume. These defaults have been selected to reduce the amount of space lost and to reduce the amount of fragmentation on the volume. For general use, default settings are strongly recommended.