|A RAID system used as a main system disk is not intended as a replacement for backing up data. In parity configurations it will provide a backup-like feature to protect from catastrophic data loss caused by physical damage or errors on a single drive. Many other features of backup systems cannot be provided by RAID arrays alone. The most notable is the ability to restore an earlier version of data, which is needed to protect against software errors causing unwanted data to be written to the disk, and to recover from user error or malicious deletion. RAID can also be overwhelmed by catastrophic failure that exceeds its recovery capacity and, of course, the entire array is at risk of physical damage by fire, natural disaster, or human forces. RAID is also vulnerable to controller failure since it is not always possible to migrate a RAID to a new controller without data loss.|
RAID drives can serve as excellent backup drives when employed as removable backup devices to main storage, and particularly when located offsite from the main systems. However, the use of RAID as the only storage solution does not replace backups.