You will need a lvm backup file for the pvcreate --uuid I believe (there may be some option to get around needing the backup file).

That will put the header back on if you either have an lvm backup and/or archive file, you might also need a vgcfgrestore afterwards depending on if anything else is missing.

I have never done it, but it looks possible to make a lvm backup file by reading it directly off the disk with dd, so that you will have a file that pvcreate is ok with, that is if there is no way to force it without a backup file.

But, this should get the pv back showing up with whatever sectors that you successfully recovered.

On Sun, Oct 17, 2021 at 10:02 PM Brian McCullough <bdmc@bdmcc-us.com> wrote:

Folks,

I have had a disk go bad on me, causing me to lose one PV.

I seem to have retrieved the partition using ddrescue, but it also seems
to be missing some label information, because pvscan doesn't see it.

Using hexdump, I see the string " LVM2 " at 0x1004, but nothing before
that. The whole phrase is:

0x01000 16 d6 8e db 20 4c 56 4d 32 20 78 5b 35 41 25 72

I find what appears to be an LVM2 configuration section at 0x1200, and
so I was able to read the UUID that this PV should have.

On another machine, I dumped a PV partition, and find "LABLEONE" at
0x200, with the same " LVM2 " at 0x01000.

I was concerned that my dump was offset, but the comparison to the
"good" one suggests that that isn't the problem, but just the missing
"LABLEONE" and related information at 0x0200.

If I do a "pvcreate --uuid xxxx" would this fix that recovered partition
so that pvscan and friends can work properly, and I can finally boot
that machine?

Thank you,
Brian

_______________________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://listman.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/