In message , at
17:03:06 on Fri, 25 Jun 2010, Jon Green remarked:
The answer to that is to lay in spare parts at the same time as the
order for the RAID unit. Yes, it increases the initial cost, but at
least you know you have the spares available in five years' time.

The best RAID controllers build that in - they have one or two spare
drives configured in, that don't initially store any data, but can be
swapped in when needed.

I suspect that Mike meant more than just the drives. If you're dealing
with mission-critical data, it's imperative to keep a hot spare RAID
box too, in secure storage away from the building, so that you can
bring up the data set ASAP after a RAID main board failure. There's
absolutely no guarantee that the drive set will work together in a
different model or make -- in fact, it's pretty-much certain they won't.

The RAID controller in one of my servers does exactly that, it imports
the drive characteristics (and hence the total storage characteristic)
from whatever is plugged in. But I agree it may have to be the same
make, but as that's Compaq it's not a huge issue.
--
Roland Perry