Supported versions of the DOS filesystem
SCO OpenServer supports the FAT12, FAT16, VFAT, and FAT32 versions of the DOS
The FAT12 and FAT16 versions
come with DOS versions up to MS-DOS 6.x, and
limit filenames to a traditional 8.3
style (an 8 character ``name'' portion and a 3 character ``extension'' portion).
Only numeric and uppercase alpha characters are allowed, and the
following special characters cannot be used:
[space] " / [ ] : * < > | + = ; ' ? .
The version of dosfs known as ``Extended FAT'' or
``VFAT'', is essentially the same as the older versions of the dosfs,
but removes some of the file naming restrictions.
A VFAT filename can be 255 characters long,
and can include lowercase alpha characters, any Unicode character,
Filenames can contain a dot (.), but cannot start with one.
Nor can filesnames contain the following special characters:
" / : * < > | ?
The rules for file names are the same in the FAT32 version
of dosfs, and in addition it improves on the performance
of the earlier versions of the filesystem in the following ways:
FAT32 supports filesystems up to 2TB in size (effectively, 128GB
because of IDE hard disk limitations).
The minimum size of a FAT32 filesystem is 512MB.
Use of disk space is up to fifteen percent more efficient than in
FAT16 filesystems because FAT32 uses smaller clusters (4K clusters
for drives up to 8GB in size).
FAT32 filesystems can be mounted faster because the operating/ system
can initialize its internal data structures without having
to read the entire FAT.
A mounted FAT32 version of dosfs can be exported as an NFS
FAT32 can relocate the root directory and use the backup copy of the
file allocation table instead of the default copy.
In addition, the boot record on FAT32 drives has been expanded to include
a backup of critical data structures.
This means that FAT32 drives are less sucesptible to a single point
of failure than existing FAT16 filesystems.
The root directory on a FAT32 filesystem can be located anywhere on the
(A previous limitation on the number of root directory entries no
The dosfs filesystem type, whichever version you have using,
does not support UNIX special files like
pipes and block/character specials, nor does it support
real or symbolic links.
The boot sector
dosfs filesystem layout
© 2007 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 -- 05 June 2007