[linux-lvm] Recovering data from an LV/VG w/ a crashed PV

[Ken Bass]

 (I know this topic has probably been brought up before, but I couldn't find
anything in the archives - if there is, please give me a link.)

I have an LV made up of 4 SCSI drives (PVs). One of those just crashed.
Specifically, the SCSI controller can't get anything but a not ready error
from it. Ergo, it is D-E-A-D. (And no, it wasn't part of a RAID :-(  ).

I've come to accept that, but now I want to know if I can recover anything
from the rest of the LV. Right now, at boot time, the LVM sees the VG with
an LV that is missing a PV, so it drops me to maintenance mode, where I
really can't do much. I can get the system to boot by physically removing
the VG (it's not my system VG), then disable it in fstab, and reboot again.
So, theoritically, I should have access to the VG/LV, missing the one dead
PV.

I can't migrate the extents off of the dead PV (duh), but can I remove that
PV from the LV/VG, and maybe recover some of the data on the other PVs?

FWIW, the filesystem is XFS. It is mainly used as a store and forward
server, and fortunately, most of the data on it had been saved. The rest of
it can be recreated, but it would be a very timely process (several days at
least). So any data that I can get off of the "amputated" LV would
definitely help.

I'm just about at the point where I will just rebuild the VG/LV from scratch
- that is, recreate a new VG/LV from the remaining PVs. But I just wanted to
know - before I commit - if I can recover anything.

Also - minor gripe - why won't the system boot if a VG has a bad LV, and
that VG is not the system VG? I'd like the LV to mount if it is okay, that
is why I have it in fstab. But, as above, when the system boots, and the LVM
sees that crippled VG/LV, the system goes to maintenance mode. Is there some
way to tell the system at mount time to continue w/o mounting that VG/LV?

As always, TIA

ken
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