File Systems

The file system is the way in which any Operating system manages files.  The key part is the FAT, or File Allocation Table.  It resides on the outer tracks of the hard drive, and is a cross-reference for all the files on the drive.  It keeps track of the starting and ending address for each sectors where each file resides on.  Files are normally fragmented, so for each file - there will be several locations.

Almost all drives today use either FAT32 or NTFS.  NTFS also uses a file table, but it is markedly different than the FAT32 table.

FAT12 -  is the only format used on floppy diskettes.

FAT16 (also called FAT) – used with DOS, Win95A, and WinNT 1.0 through 4.0 Service Pack 3 - but can be recognized by all Windows operating systems.  See MS Article Q100108 for info on FAT, HPFS (not covered here – rare) and NTFS.  See MS Article Q140365 for default cluster sizes with FAT and HPFS.   FAT16 has no backup copy of the indices!!

FAT32 – used with Win95B (Win95 OSR2), Win98, Win98SE, Windows ME, Windows 2000, and Windows XP  -  DOS, Win95A, and WinNT cannot read a FAT32 volume !!  The boot record on FAT32 drives is expanded to include a backup copy of critical data structures.  MS-DOS, the original version of Microsoft Windows 95, and Microsoft Windows NT 4.0-and-earlier do not recognize FAT32.  File size limit is one byte less than 4 GB on a FAT32 partition.  However, for AVI files the limit is 2 GB.

See MS Article Q154997 for general info on FAT32 and Q253774 for a FAT32 FAQ and MS Article Q310525 for info on FAT32 on WinXP.  See MS Article Q184006  for FAT32 limitations.

NOTE1:  Windows 2000 only supports FAT32 partitions up to a size of 32 GB !!  Also, A FAT32 volume cannot be compressed by using Microsoft DriveSpace.

NOTE2:  for Win2000 and XP, NTFS is recommended over FAT32 – more stable. To convert a FAT32 volume to NTFS see MS Article Q307881 – use the included file, “convert.exe” by opening a DOS box and typing :

convert drive letter: /fs:ntfs

NOTE:   if the system cannot gain exclusive use of the drive – it will ask you if you want to convert upon the next reboot – say “Y” and then reboot

NTFS (NT File System) – used with WinNT 4 Service Pack 4 (and up), Windows 2000, and Windows XP  -  DOS, Win95A, Win95B (Win95 OSR2)Win98, Win9898 SE, and Windows ME cannot read an NTFS Volume !!  Only Microsoft Windows 2000 and Windows XP have full access to files on an NTFS volume (NT 4.0 SP4 and up have some imitations with recent versions of NTFS).