Okay. Here's what i'd do if you're wanting this RAID system to help redundancy AND be a backup. Firstly, be sure to use a physical RAID card. Don't trust it to software, you're just asking for more problems than necessary (although the motherboard controlled RAID's all right for home use). Secondly you should buy another HD for backup purposes. At the end of an allocated amount of time (day, week, month) pull one of the drives in the array, and slip in the spare drive. It will mirror, and you'll have a snapshot of your system when you pulled the drive. If you screwed everything up, you can slip the 'Backup' drive back into the array and everything's restored back to that point right away. This would work for some users, and may for you. But it depends on what your exact backup needs are.

Okay. Here's what i'd do if you're wanting this RAID system to help redundancy AND be a backup. Firstly, be sure to use a physical RAID card. Don't trust it to software, you're just asking for more problems than necessary (although the motherboard controlled RAID's all right for home use). Secondly you should buy another HD for backup purposes. At the end of an allocated amount of time (day, week, month) pull one of the drives in the array, and slip in the spare drive. It will mirror, and you'll have a snapshot of your system when you pulled the drive. If you screwed everything up, you can slip the 'Backup' drive back into the array and everything's restored back to that point right away. This would work for some users, and may for you. But it depends on what your exact backup needs are.