[linux-lvm] Device mapper problems..

Fabian Herschel fabian.herschel at novell.com
Thu Sep 15 16:02:34 UTC 2005

You have a look which device path is used when mounting your both file
systems (using mount).
Than you can have a look at the major and minor device number of these
devices (using ls -la).
If these devices are using the same major/minor combination the kernel
assumes these devices
the be the same. This would show the effects you mentioned.

ls -la /dev/mapper/*
brw-------  1 root root 253, 3 Jun 21 16:09 /dev/mapper/rootvg-homlv
brw-------  1 root root 253, 2 Jun 21 16:09 /dev/mapper/rootvg-optlv

in this case rootvg-homlv has major 253 and minor 3, while rootvg-optlv
has major 253 and minor 2.

best regards
Fabian Herschel

Suleyman Kutlu schrieb:

> Hello all,
> I have an AMD-64 machine running SuSE 9.2. I have one SATA disk (for
> now, will add another later on) and a VG on it. I have created some LVs.
> Sometimes later, I realized that when I mount an LV (say lv_a) I see
> the directory structure of another LV (say lv_b). If I issue a df -k,
> I see a wrong size for lv_a, it is the size of lv_b. But in lvdisplay
> output, the size for lv_a is correct.
> The file systems on lv_a and lv_b is JFS.
> /mnt is mounted as lv_b
> /mnt2 is mounted as lv_a but has contents of lv_b
> I thought that, filesystem structure is corrupted and started to work
> on some filesystem level utilities, but later I see that,
> another filesystem pair also got the same problem.
> So I think it is a problem in device-mapper level, not the filesystem
> level.
> What can be the possible works to get what is wrong and how to fix ?
> If the corruption is at filesystem level, do you have any experience
> on JFS-utils ? I just want to see what was stored in lv_a, what I lost
> in lv_a...
> I am new at device-mapper, I don't have enough experience on it and I
> do not want to loose everything while there is something that can be
> recovered...
> Any help is appreciated.
> Thanks and regards..
> * Suleyman Kutlu
> * mailto: suleyman.kutlu at gmail.com
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> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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