Hello,
As I know if MD raid is using the newer metadata version, it support
resumable raid rebuild/sync. (that is, if a server is rebooted during
rebuild, it would resume from last position after reboot, instead of
starting from beginning).
In my recently testing (a few months ago):
I sometimes use the mdadm 'check' action for doing the disk scrubbing
of a MD raid.
After I rebooted the server, the 'check' operation is forgotten and is
not resumable.
I think resumable 'check' operation is useful as the array size would
become bigger in the future.
Thanks and regards,
Patrick