Hi,
I have a working RAID6, consisting of seven disks.
I'd like to change all disks, because we suspect problems with the
drive types / controller combination.
On top, I'd like to reduce the number of disks to six - the seventh
disk was added during a operations test and the added space is not
actually needed. (The upper layers still see the size of the RAID
device as it was when only six disks were used).
The server chassis has 12 slots, ten of which are available to the
RAID disks (seven disks, plus three empty slots).
As a first step, I inserted three of the new disks into the empty
slots, added them as spares to the RAID set and ran mdraid --replace
for three of the old disks.
The question is, how do I optimally continue once the first three
disks are replaced and the according three old disks are removed. Can
I both replace and resize in a single (or almost single) step?
I had hoped that something along the following might work:
- fail one of the remaining 4 old drives
- mark the other three old drives for replace
- reshape the RAID to 6 disks (which probably will start right away)
- insert the three new disks and add them as spares
which then *might* result (after the resync) in four old disks marked
as faulty, leaving me with a six-disk RAID6 consisting of only the new
disks.
Am I on the right track, or will I have to run this in individual
steps (replace three more disks, then fail the remaining old disk,
then reshape)?
The data is fully backed up and replicated live to another server, so
the reduced resiliency to disk failure is less of a problem. But I'd
like to do an online replacement, without taking days. The new disks
are much faster than the old ones, too.
Thank you for any insight, ideas or comments you'd like to share.
Regards,
Jens
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