Ok redundancy is not backing up. It's a very popular misconception. Raid 1 mirrors a drive onto a second drive. The drives run simultaneously. In the event of a HD failure the computer continues to run. The redundancy allows the system to continue to run without interruption. Redundancy is useful for servers where the information must always be available.
While it's true that the data is saved by the RAID 1, RAID is not designed for backup purposes. A backup is designed to make data recoverable in the event the data is destroyed. Here are some examples where the difference in definition is worth knowing.
1. Because the RAID 1 runs continuously and without user intervention, if the data is corrupted or lost by user error it...