Quote:
There is an --assume-clean option which is safe for raid1 and raid6 but for raid5 it is NOT safe to skip the initial sync.


Why would this be safe for raid 6, but not raid 5? Both use distributed parity for the redundancy. Raid 6 simply has a different algorithm in use across the drives to ensure any 2 disks can fail, by using 2 disks worth of space for the parity.