Hot-swapping disks of different size in a RAID set

Hi there:

We have a 9406-525 with 8 4327 (70 GB) disk drives in a single RAID set.
The drives are in the system enclosure and there are no additional slots
available. We are at 85% DASD utilization.

We have an idea for increasing our DASD capacity without taking our
system down. Our thought is that we could fail one of the 4327 drives,
replace it with a 4328 (140 GB) or 4329 (280 GB) and let the RAID
controller rebuild it, and that we could do this one-by-one until we
have replaced all of the drives, thus doubling or tripling our current
DASD.

Is this totally crazy? One person I've talked with suggested that you
can't have mixed sized disks in one RAID array, but our network admin
thinks we did have this in an 810 we used to run. Someone else thought
that we might have issues increasing our DASD capacity without
increasing disk arms, but our current performance metrics don't seem to
support that concern. At any rate, we are willing to take that risk.
Our main interest right now is answering the question about whether or
not this disk-at-a-time replacement into the same RAID array is
possible. We really can't afford to have our system down for the time
it would take to do the backup/change disks/restore method.

Thoughts?

Thanks,

Johnny Lee Lenhart
Sr. Technical Specialist
Brattleboro Memorial
Hospital
Brattleboro, Vermont USA


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