On Ubuntu 20.04 AMI, scylla_raid_setup --raiddev /dev/md0 causes
'/dev/md0 is already using' (issue #7627).
So we merged the patch to find free mdX (587b909).
However, look into /proc/mdstat of the AMI, it actually says no active md device available:
ubuntu@ip-10-0-0-43:~$ cat /proc/mdstat
Personalities :
unused devices: <none>
We currently decide mdX is used when os.path.exists('/sys/block/mdX/md/array_state') == True,
but according to kernel doc, the file may available even array is STOPPED:
clear
No devices, no size, no level
Writing is equivalent to STOP_ARRAY ioctl
https://www.kernel.org/doc/html/v4.15/admin-guide/md.html
So we should also check array_state != 'clear', not just array_state
existance.
Fixes#8219Closes#8220
2d9feaacea