As someone mentioned above RAID controllers can go bad too, and then you're really up a creek. I've had 2 OWC externals RAIDs kick the bucket before their HDs did. In one case I was able to recover the data, in the other not. This has taught me that digital is not now 'archival' as we think of it in film terms. I think mirrored 2 bay drives are the way to go. If the controller kicks the bucket you can yank out one or both drives and read them just fine, and you can transfer them most easily.
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