File Systems

For small volumes, FAT16 or FAT32 might provide nominally faster access to files than NTFS because:

• The FAT structure is simpler.

• The FAT folder size is smaller for an equal number of files.

• FAT has no controls regulating whether a user can access a file or a folder; therefore, the system does not have to check that a user has access permissions to a file or folder. This advantage is minimal, however, because Windows 2000 still must determine whether the file is read-only, or whether the file is on a FAT or NTFS volume.

NTFS minimizes the number of disk accesses and time needed to find a file. In addition, if a folder is small enough to fit in the Master File Table (MFT) record, NTFS reads the entire folder when it reads its MFT record.

A FAT folder entry contains an index of the file allocation table, which identifies the cluster number for the first cluster of the folder. To view a file, FAT has to search the folder structure.

For operations performed on large folders containing both long and short file names, the speed of a FAT operation depends on the operation itself and the size of the folder. If FAT searches for a file that does not exist, it needs to search the entire folder— an operation that takes longer on a FAT structure than on the structure used by NTFS.

Several factors affect the speed with which Windows 2000 reads or writes a file:

• If a file is badly fragmented, NTFS usually requires fewer disk accesses than FAT to find all of the fragments.

• For both file systems, the default cluster size depends on the volume size, and is always a power of 2. FAT16 addresses are 16 bits, FAT32 addresses are 32 bits, and NTFS addresses are 64 bits.

• The default cluster size for a FAT16 volume is always larger than the default cluster size for either a FAT32 or an NTFS volume of the same size. The larger cluster size for a FAT16 volume, however, means that there might be less fragmentation in files on a FAT16 volume.

• With NTFS, the MFT record can entirely contain small files; FAT contains pointers to files. The file size that fits within the MFT record depends on the cluster size and the number of attributes for the file.