Fragmentation refers to the tendency of files stored in the FAT file system to
become broken into pieces that can end up in very different places within a hard disk
volume. How fragmentation occurs is explained in detail here.
A fragmented file system leads to performance degradation. Instead of a file being in
one continuous "chunk" on the disk, it is split into many pieces, which can be
located anywhere on the disk. Doing this introduces additional positioning tasks into what
should be a sequential read operation, often greatly reducing speed. For example, consider
a 100,000 byte file on a volume using 8,192 byte clusters; this file would require 13
clusters. If these clusters are contiguous then to read this file requires one positioning
task and one sequential read of 100,000 bytes. If the 13 clusters are broken into four
fragments, then three additional accesses are required to read the file, which could
easily double the amount of time taken to get to all the data.
Defragmenting a very fragmented hard disk will often result in tangible improvements in
the "feel" of the disk. To avoid excessive fragmentation, defragment on a
regular basis; usually once every week or two is sufficient. See the system care guide for
more.
Next: Disk Compression
