[lug] Semi-OT, Linux and Mac read VFAT

D. Stimits stimits at attbi.com
Sat Sep 28 13:59:35 MDT 2002

Timothy C. Klein wrote:
> Hello all,
> I find myself on Campus these days at a Mac machine quite a bit.  I had
> a Zip disk with a VFAT file system on it.  It had a couple things on it,
> and I could read them at home.  I then used the Zip disk in a Mac with
> OS9 at school, which worked fine.  It saw the files, allowed me to write
> to the disk.  However, when I get the disk home, I am getting nothing
> but gibberish when the device is mounted.  What I see changes each time
> I mount the disk, doing an 'ls' in the mounted directory will screw up
> the terminal, the kernel complains of this:
> Sep 25 22:08:18 i148 kernel: attempt to access beyond end of device
> Sep 25 22:08:18 i148 kernel: 03:44: rw=0, want=65792, limit=10668
> So something obviously got corrupted.  Does anyone know if a Mac and
> Linux can play nice on a VFAT file system?  Was this a fluke?  I suppose
> I could use the Mac filesystem, (what is it, HPFS or something), but I
> am then stuck if I get stuck at Windows machine.  
> I have never really used a Mac for much of anything, so I have no
> experience with interoperability.
> Thanks for any advice,

I don't know if they play nicely or not, but what you might try to do is 
run fdisk on the zip (probably just one huge partition) from linux, and 
see what it says the boundaries are. Then mount it for read under linux, 
umount it, check it again...likely nothing has changed. Now go to the 
Mac, mount it, maybe do something that is read-only, and bring it back 
to linux. Compare boundaries again under linux fdisk, without actually 
mounting it. Could be there is some difference in what is expected, and 
the Mac might be silently "fixing" it for you, causing it to break. Oh, 
you can also tell linux in its mount command to do the mount read-only. 
In any case, run the sync command under linux just to be sure, before 
you umount from it.

D. Stimits, stimits AT attbi.com

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