Bob,
I think you’re misunderstanding the “rebuilding” process. When a SINGLE drive goes bad in a raid 5 config, you may continue to work accessing that raid set. You may experience slightly lower performance, but you still can use the raid… that’s the whole point! The “rebuild” process is typically a ‘background” activity, so while it may take hours to complete, it really doesn’t impact workflow that significantly.
Our entire SAN is based on Raid 5 level security. We’ve been up and running for over five years and haven’t missed a broadcast deadline yet. During that time we’ve probably replaced and “rebuilt” over a dozen individual drives. At around the three year mark, it seemed that drives were dropping like flies, and we were popping in new drives just about every week. Since then, it’s stabilized and we haven’t had a drive go bad in awhile. But, make no mistake, EVERY drive will die if you run it long enough. That’s why they invented the RAID schemes.
Having said all of the above, when we’re facing a critical deadline, I make sure that essential media lives somewhere OTHER than our primary SAN, like on a the internal drives of one of our computers. You’re absolutely correct that “time to restore” media if the whole SAN goes done should be considered. I always have the original media on disk or tape, but by the time I recreated what I need, my deadline would have passed. So, if you’re down to the wire, make sure you have a plan “B”.
Mark