.. helping OP:
RAID, in simple terms, is a setup of disks, where the server sees them as 1 logical disk unit. the main usage is redundancy, most common RAID1 means that the drives are mirrored (whatever you save on 1 drive, you save on another drive as well), and if you have a drive failure, you have a spare. .. that's in short. the problem with your question > it does not protect you if you need to recover an older version of your website (for example, if it gets hacked or killed by a fresh update).