Hi Daniel, On 4/1/20 2:07 PM, Daniel Jones wrote:
Hi Phil, So far so good.
Yes.
# mdadm --manage /dev/md0 --add /dev/mapper/sdb1 mdadm: added /dev/mapper/sdb1
Don't do this. Overlays can't really handle the amount of data that would be involved, and you definitely don't want to rebuild yet.
4: Summary The drives have had physical partitions written. I think I've found the correct offset and device order to use --create to restore the array to the degraded state it was in before the superblocks were overwritten.
Yes.
I'm not sure why the --add doesn't work.
Don't do the --add operation until you've copied anything critical in the array to external backups (while running with 3 of 4). The reason is that any not-yet-discovered URE on those three will certainly crash the array during rebuild. It could still crash copying critical stuff, but you can repeatedly --assemble --force to keep going with the next items to backup.
Only when you've backed up everything possible do you --add the fourth drive back into the array.
Thanks so much for your help this far.
You're welcome.
Regards, DJ
Phil
