[linux-lvm] can't mount vfat fs on lvm created by winxp guest on xen

[linux-lvm] can't mount vfat fs on lvm created by winxp guest on xen

[Yann Boutin]

Greetings, 
I've had no success with mounting a vfat file system created by a 
Windows XP guest on a lvm volume. Windows XP guest is running under xen 3.0.5 rc3.

# mount -t vfat /dev/vg1/win1 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/vg1/win1,
       missing codepage or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

# dmesg
FAT: invalid media value (0xb9)
VFS: Can't find a valid FAT filesystem on dev dm-0.

# lvm version
  LVM version:     2.02.10 (2006-09-19)
  Library version: 1.02.10 (2006-09-19)
  Driver version:  4.7.0

# uname -a
Linux gentoo 2.6.18-xen #6 SMP Sun Apr 22 12:11:43 CEST 2007 i686 
Intel(R) Core(TM)2 CPU          6300  @ 1.86GHz GenuineIntel GNU/Linux


I found solutions for similar problem (symptoms) reported with usb pens but no one worked.

Help  would be greatly appreciated.

Thanks!

	Yann.

Re: [linux-lvm] can't mount vfat fs on lvm created by winxp guest on xen

[Bryn M. Reeves]

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Yann Boutin wrote:
> Greetings, 
> I've had no success with mounting a vfat file system created by a 
> Windows XP guest on a lvm volume. Windows XP guest is running under xen 3.0.5 rc3.
> 
> # mount -t vfat /dev/vg1/win1 /mnt/
> mount: wrong fs type, bad option, bad superblock on /dev/vg1/win1,
>        missing codepage or other error
>        In some cases useful info is found in syslog - try
>        dmesg | tail  or so
> 

Presumably, the windows install partitioned the raw storage?

Try running "file -s /dev/vg1/win1". If it says something like this:

/dev/sda: x86 boot sector; partition 1: ID=0x83, active, starthead 1,
startsector 63, 208782 sectors; partition 2: ID=0x8e, starthead 0,
startsector 208845, 195157620 sectors, code offset 0x48

Then there's a partition table on the device and the VFAT file system is
in a partition on it.

You can map those partitions using kpartx. Run:

kpartx -a /dev/vg1/win1

And you should see some new entries in /dev/mapper like win1p1 win1p2
etc. You can remove them with:

kpartx -d /dev/vg1/win1

Regards,
Bryn.

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Re: [linux-lvm] can't mount vfat fs on lvm created by winxp guest on xen

[Yann Boutin]

On 15:05 Sat 28 Apr     , Bryn M. Reeves wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Yann Boutin wrote:
> > Greetings, 
> > I've had no success with mounting a vfat file system created by a 
> > Windows XP guest on a lvm volume. Windows XP guest is running under xen 3.0.5 rc3.
> > 
> > # mount -t vfat /dev/vg1/win1 /mnt/
> > mount: wrong fs type, bad option, bad superblock on /dev/vg1/win1,
> >        missing codepage or other error
> >        In some cases useful info is found in syslog - try
> >        dmesg | tail  or so
> > 
> 
> Presumably, the windows install partitioned the raw storage?
> 
> Try running "file -s /dev/vg1/win1". If it says something like this:
> 
> /dev/sda: x86 boot sector; partition 1: ID=0x83, active, starthead 1,
> startsector 63, 208782 sectors; partition 2: ID=0x8e, starthead 0,
> startsector 208845, 195157620 sectors, code offset 0x48
> 
> Then there's a partition table on the device and the VFAT file system is
> in a partition on it.
> 
> You can map those partitions using kpartx. Run:
> 
> kpartx -a /dev/vg1/win1
> 
> And you should see some new entries in /dev/mapper like win1p1 win1p2
> etc. You can remove them with:
> 
> kpartx -d /dev/vg1/win1

Actually I solved my problem the same way but by hand. I map the first inner partition with dmsetup with adding an offset of 63 blocks. But really thanks for your answer and Kpartx is much simplier.

I've started a similar thread here too :
http://lists.xensource.com/archives/html/xen-users/2007-04/msg00846.html

Best regards

   Yann.