[linux-lvm] recover volume group & locical volumes from PV?

[Rainer Fügenstein]

hi,

> I don't understand how this could have happened by accident.
> lvm2 provides strong detection of duplicated devices.
> It also detects older metadata.

that's what also puzzles me, since I've never had any issues in this 
regard before.

> So you would have to put in 'exact' but just old 'copy' of your device
> and at the same time drop out the original one -  is that what you've 
> made ??

no. this is what happened: (from memory)

/dev/sda5 = only PV containing vg_sh64

about 2 months ago:

pvcreate /dev/sdc1 (temp. HD)
vgextend vg_sh64 /dev/sdc1
pvmove vg_sh64 /dev/sda5     (move VG from old to temp HD)
vgreduce vg_sh64 /dev/sda5

- replace "old" sda with a new, bigger one
- create same partition layout

pvcreate /dev/sda5
vgextend vg_sh64 /dev/sda5
pvmove vg_sh64 /dev/sdc1   (move everything back to new HD)
vgreduce vg_sh64 /dev/sdc1

what I *DID FORGET* then was to issue "pvremove /dev/sdc1"

a few days ago, I inserted the old temp HD sdc into the SATA hot swap 
bay and powered it on. shortly after that the system behaved strangely. 
issued "dmesg" and saw a lot of error messages regarding SATA. 
unfortunately, memory is blurry from then on since I entered panic mode.

Did a graceful shutdown though (closed all programms, executed 
"poweroff"). from this moment on, VG on /dev/sda5 was gone.

can't rule out that powering on sdc in the hot plug bay caused havoc on 
the SATA bus, just when lvm was doing some housekeeping.

> VG & LV are just 'terms' - there is no 'physical-conte
> lvm2 provides command:  'vgcfgrestore' - which can restore your older 
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

thanks for the information (also to Roger). I managed to recover a 
promising LVM text file from lost+found on the temp disk. will try to 
restore it as soon as I'm back home again.

thanks - and wish me luck ;-)