Say, I have 3 HDDs in single volume group. One of the drives had crashed and I need to replace that. In the past I used ddrescue to recover entire drives/partitions, sometimes I had limited time to work with a drive, after recovering part of the drive, the drive would stop responding.
Say in my 3 HDD vg, I have 10 logical volumes and only one is the precious one I want to recover.
I could use ddrescue on entire failing HDD, but the HDD may die in the middle of that process, possible recovering blocks that I don't care. I thought, I could minimize number of reads from the HDD by reading only PE from a volume I care about.
Say the LVM metadata is corrupted but I have LVM metadata backup.
How do I go about creating sector copy from a 'precious volume'?
Do I have to start LVM and have ddrescue to work on LVM precious volume device ?
or are there any other methods w/o starting LVM to recover precious volume blocks ?