[nzlug] LVM and toast....

[Nevyn]

Hi,

Things are going very badly at the moment - suddenly the output of
/proc/mdstat was showing that 2 disks had suddenly dropped off - 1 was
showing a failure and I have no idea why the other one wasn't in there
except that it was showing (s) next to it.

Of course this meant that suddenly the array wasn't working which
explains all the wierd behaviour I had suddenly started experiencing.
After a few failed attempts to get the array to rebuild itself, I
reboot the machine and lo and behold, the raid seems to have gotten
itself together.

Still wasn't mounting though so I ran vgscan - and got the following message:
  Reading all physical volumes.  This may take a while...
  Incorrect metadata area header checksum

The lvm howto has this to say about it:
"If you get the warning "incorrect metadata area header checksum" or
something about not being able to find PV with UUID foo, you probably
toasted the volume group descriptor area and lvm startup can't occur."

and then has a command to restore the stuffed bits:
pvcreate --uuid "<some_long_string>" --restorefile
/etc/lvm/archive/VolumeGroupName_XXXXX.vg <PhysicalVolume>

However, I don't have a .vg file anywhere that I can find. There is a
file in the back up directory but I'm a little unsure about this as it
doesn't have a .vg extension.

Does anyone know how I can fix all this?

Regards,
Nevyn.