Sample DOSFS disk image file for testing

On Jun 18, 4:53=A0pm, CBFalconer <cbfalco...@yahoo.com> wrote:
> "robertwess...@yahoo.com" wrote:
> > Vladimir Vassilevsky <antispam_bo...@hotmail.com> wrote:
> >> robertwess...@yahoo.com wrote:
>
> >>> My mistake - I was editing and got a FAT16 comment mixed in
> >>> with the FAT32 comment. =A0FAT32 volumes cannot be smaller than
> >>> 32MB, and FAT16 volumes must be smaller than 2GB. =A0FAT32
> >>> volumes can be up to 2TB.
>
> >> Why 2 TB ? 28 bit FAT x 32k cluster =3D 8 TB.
>
> > There's a 32 bit sector count field in the BPB (at +32). =A0If
> > that got patched, I don't know of anything that would prevent an
> > 8TB volume.
>
> The systems using the file system have to keep track of file size.
> They can't measure things larger than 2GB in an int (which they
> need, in order to handle negative offsets in the software).
> Allowing files to grow above 2GB would lead to nasty undetectable
> errors when the file grew past 2GB.


Current FAT32 implementations handle 4GB files just fine (FAT16 can't
support a volume big enough for that size file unless you use large
sectors, FAT12 can't support that big a volume period).  I could
certainly believe that some older ones squawked, or that you might
find an unusual one with an issue.  Applications are also vulnerable
to bugs at that point (and I'm certain we could find plenty that had
problems at that point), but that's a bit of a different issue.

I remember when file sizes first started bumping past 2GB on
mainframes - we definitely ran into problem both in the file systems
(especially VSAM), and in applications (although since these tended to
all be structured files, it was more often the file system with
issues, since the application typically didn't use that offset
directly).

NTFS (along with many other file systems) support files far in excess
of 4GB.  All the native Win32 file APIs use 64 bit values for offsets
(even on FAT =96 you just can=92t create a file big enough to use the high
word there), although in some cases there have been a couple
iterations of those - the original using a pair of 32 bit values, and
a more recent one using a 64 bit value).  Again, I'm sure there are
applications with issues at both 2GB and 4GB.

The 4GB file size limitation on FAT is a problem for many
applications, like media ones, which can produce quite large files,
and some actually go to the trouble of segmenting files so that your
video source ends up as multiple 4GB files on your 100+GB volume.  Or
just insist on NTFS...

And we are talking volume sizes, not file sizes.