|You will still need to partition and format the new hard disk. Every hard disk is partitioned, even it is a single partition than spans the whole disk.|
RAID is not a backup and backup is not RAID.
They two completely different procedures for two completely purposes. If a home user has a disaster, they use a backup. It matters little that their data is unavailable for a few hours while the restore is done, something that RAID is designed to avoid. It duplicates stuff that has no need to be duplicated and therefore wastes storage space.