Re: Requesting assistance recovering RAID-5 array

Daniel Jones
2020-04-03T18:42:16Z

After the "--create missing /dev/sdc1 /dev/sdd1 /dev/sde1" and the
fsck, is "mdadm --manage /dev/md0 --add /dev/sdb" the correct syntax
for attempting to add?

-DJ

On Fri, Apr 3, 2020 at 12:34 PM Phil Turmel <philip@turmel.org> wrote:
>
> On 4/3/20 2:29 PM, Daniel Jones wrote:
> > Hello again,
> >
> >> Don't do the --add operation until you've copied anything critical in the array to external backups (while running with 3 of 4).
> >
> > Everything from the array has been backed up elsewhere.
> >
> > Up until now the only writes intentionally done to the physical drives
> > have been the new partition tables. Everything else has been through
> > the overlay.
> >
> > Now I think I'm ready to run a --create as follows on the physical drives:
> > mdadm --create /dev/md0 --assume-clean --data-offset=129536 --level=5
> > --chunk=512K --raid-devices=4 missing /dev/sdc1 /dev/sdd1 /dev/sde1
> >
> > After that I'd try to re-add the rejected drive?
> > mdadm --manage /dev/md0 --add /dev/sdb1
> >
> > Part of me wonders about just rebuilding the whole thing and then
> > copying the data back, but I don't know that would be any better then
> > this path.
>
> Sounds like a risk-free decision. mdadm --create --assume-clean
> followed by a proper fsck will be lots faster than mdadm --create, mkfs,
> and copying.
>
> I'd go fast.
>
> Phil