microsoft FAT

Concept

• uses FAT allocation
• free space management - handled by the FAT

Special FAT

• next block number
• FREE code
• EOF code - last block in file
• BAD code - bad block on the physical storage

Directory

• special type of file
• root dir stored in fixed loation
• other files/sub-directories are directory entries

Variants

• support larger disks as a single partition
• disk cluster - group of contiguous disk blocks
  • larger clusters -> larger partition for same FAT size
  • larger clusters -> more internal fragmentation
• FAT size - determines the number of blocks/clusters

FAT12

• clusters

FAT16

• clusters

FAT32

• clusters

VFAT

• support for long fine name
• use multiple directory entries to store the full filename
• 8-3 naming for backward compatibility