Subj : Re: FAT/dosfsck oddity
To   : comp.os.linux
From : robertharvey
Date : Thu Aug 19 2004 03:23 am

pandora_xero@hotmail.com (Pandora Xero) wrote in message news:<390dc7e9.0408170444.5641fb92@posting.google.com>...
> I get a message like "dosfsck currently only supports 2 allocation
> tables, not 191"
> I have never had such an error message before, but dosfsck seems to be
> saying that for both of the FAT32 disks on this machine. both of said
> drives were formatted using MS-Windoze.
> I thought the FAT structure itself only supported 2 "Allocation
> Tables" if so, then why the hell am i getting a message like this?
> perhaps dosfsck is not reading something on the drives incorrectly?
> any help on this matter would be greatly appreciated, as it seems the
> crapware "Scandisk" prog that comes with Windoze isn't seeing this
> problem, and is thus not doing anything to fix it.

Right.  At byte offset 10h whithin the FAT32 Boot Sector/Boot Record
Layout. is a byte containing "number of FATs".  This can hold any
value from 0 to 254, but it is almost always set to 2.  Windoze almost
certainly does not read it at all, it probably only assumes it is 2. 
No Dos or other legacy code would handle more than 2, so setting it
higher probably doesn't achieve anything.

You can specify things like mkdosfs -f 191 under linux, but it won't
do anything userul.


My guess is that yours is corrupt.  Widnoze doesn't care, it isn't
looking.  dosfsck is.   dosfsck probably has no tools for fixing this,
so running -a or -r won't help.  mkdosfs can be run to format it
again.  If you want to try to rescue it, try a disk sector editor like
http://lde.sourceforge.net/

.