Backing up hardware RAID arrays (Linux)
Hardware RAID arrays under Linux combine several physical drives to create a single partitionable disk. The special file related to a hardware RAID array is usually located in /dev/ataraid. You can back up hardware RAID arrays in the same way as ordinary hard disks.
Physical drives that are part of hardware RAID arrays may be listed alongside other disks as if they had a bad partition table or no partition table at all. Backing up such disks does not make sense as it won’t be possible to recover them.