I have RAID6 on 24 drives. The raid was setup with
mdadm, so it is a software raid. One of the drives died and the server freezed due to that, so it had to be rebooted using Power Cycle (power off + power on).
When the server booted, it started the RAID array with 23 devices, and it started resync operation. If I understand it correctly, this resync just reads data on all drives and checks if everything is all right, no writes are performed. I can confirm this by
iostat -m 1 which shows only reading.
So I've replaced the faulty drive by a new one, and I would like to start REBUILD, so it actually writes data to the newly added device. I have issued the following command:
mdadm --add /dev/md0 /dev/sdc # this adds sdc to the array
It went smoothly, however the raid is still resyncing, not rebuilding. The drive is reported as spare (S) in /proc/mdstat, and it probably waits for the resync to finish in order to start rebuild.
I have to say that I don't care about resync, I need it stopped immediately and start rebuild immediately. Is there any way to do that? Thank you