Re: [linux-lvm] hardware snapshots: uuid issue

[Greg Freemyer <greg.freemyer@gmail.com>]

I use XFS when I am going to use snapshots.

It has a mount option to ignore the UUID conflict.


On Thu, 6 Jan 2005 17:14:34 +0100, gilles.massen@restena.lu
<gilles.massen@restena.lu> wrote:
> Hello everyone,
> 
> Some time ago I had a problem accessing a hardware snapshot of an LVM2
> partition. The reason: different physical volumes having the same UUIDs.
> The advice I was given was to use the "pvchange --uuid" command, but I'm
> unable to use that command whitout making the PV unusable.
> 
> What happens is this: the PV is there, it is found, but  becomes an
> "unknown" device. pvdisplay and pvdisplay <device> disagree somewhat,
> andit seems as if the old uuid is sticking around. vgscan or pvscan are of
> no use.
> 
> Now I have no idea what else to try... BTW, I also failed having two
> instances of LVM by setting LVM_SYSTEM_DIR: the second instance still
> finds the PVs of the first even...even with the appropriate filters.
> 
> Any ideas how to continue here? For the time beeing the hardware snapshots
> are not very useful...
> 
> Best,
> Gilles
> 
> Example: initial pvdisplay:
> 
>   --- Physical volume ---
>   PV Name               /dev/sdb1
>   VG Name               vg-test
>   PV Size               1020.00 MB / not usable 0
>   Allocatable           yes (but full)
>   PE Size (KByte)       4096
>   Total PE              255
>   Free PE               0
>   Allocated PE          255
>   PV UUID               v3Oknf-6Rqa-Gh72-k0GO-c3I6-eoKS-odPWVr
> 
> # pvchange -v --uuid /dev/sdb1
>     Using physical volume(s) on command line
>     Finding volume group of physical volume "/dev/sdb1"
>     Archiving volume group "vg-test" metadata.
>     Updating physical volume "/dev/sdb1"
>     Creating volume group backup "/etc/lvm/backup/vg-test"
>   Physical volume "/dev/sdb1" changed
>   1 physical volume changed / 0 physical volumes not changed
> 
> #pvdisplay -v
>     Scanning for physical volume names
>   Couldn't find device with uuid 'GaTpFU-XgFz-HRH2-Mtyb-GI1f-4LN4-TOe8FK'.
>   --- Physical volume ---
>   PV Name               unknown device
>   VG Name               vg-test
>   PV Size               1020.00 MB / not usable 0
>   Allocatable           yes (but full)
>   PE Size (KByte)       4096
>   Total PE              255
>   Free PE               0
>   Allocated PE          255
>   PV UUID               GaTpFU-XgFz-HRH2-Mtyb-GI1f-4LN4-TOe8FK
> 
> or else:# pvdisplay -v /dev/sdb1
>     Using physical volume(s) on command line
>   Couldn't find device with uuid 'GaTpFU-XgFz-HRH2-Mtyb-GI1f-4LN4-TOe8FK'.
>   Couldn't find all physical volumes for volume group vg-test.
>   format_text: _vg_read failed to read VG vg-test
>   Couldn't find device with uuid 'GaTpFU-XgFz-HRH2-Mtyb-GI1f-4LN4-TOe8FK'.
>   Couldn't find all physical volumes for volume group vg-test.
>   format_text: _vg_read failed to read VG vg-test
>   --- NEW Physical volume ---
>   PV Name               /dev/sdb1
>   VG Name
>   PV Size               1023.62 MB
>   Allocatable           NO
>   PE Size (KByte)       0
>   Total PE              0
>   Free PE               0
>   Allocated PE          0
>   PV UUID               v3Oknf-6Rqa-Gh72-k0GO-c3I6-eoKS-odPWVr
> 
> # pvscan -v
>     Wiping cache of LVM-capable devices
>     Wiping internal cache
>     Walking through all physical volumes
>   Couldn't find device with uuid 'GaTpFU-XgFz-HRH2-Mtyb-GI1f-4LN4-TOe8FK'.
>   PV unknown device      VG vg-test   lvm2 [1020.00 MB / 0    free]
>   PV /dev/cciss/c0d0p6   VG data-vg   lvm2 [8.00 GB / 0    free]
>   Total: 2 [9.00 GB] / in use: 2 [9.00 GB] / in no VG: 0 [0   ]
> 
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