KZPSC, hot spares

From: Michael A Crowley <mcrowley_at_MtHolyoke.edu>
Date: Mon, 30 Nov 1998 18:35:30 -0500 (EST)

Clearly having a disk as a hot spare on a KCPSC that is smaller in
size than the disks in a RAID 5 array is a bad idea. The documentation
even says so. ;)

I've done some experiments and have empirically determined that with
two 3-disk arrays, a hot spare will serve if a disk from either array
dies (or is pulled out).

The machine is now in production so I can't test to find out the answers
questions raised by the following situation:
I have a 8-disk array of 9 Gig drives with a 9 gig hot spare. I'd like
to make another RAID 5 array of four 18 Gig drives on the same controller.

   1. Is the thing smart enough to not try and use the 9 gig hot spare
       if one of the 18 gig drives dies?
   2. If I had both a 9 gig hot spare and an 18 gig hot spare, will it
       use the appropriately sized drive if I set up two hot spares, one
       9 gig and one 18 gig?
   3. If I used an 18 gig drive for the hot spare and a 9 gig drive
       dies, would it rebuild satisfactorily on the 18 gig spare?
   4. Should I make life easier and buy another kzpsc for the 18 gig drives?

thanks,
-mike
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   Michael A. Crowley Director of Networking
   mcrowley_at_mtholyoke.edu 216 Dwight Hall, Mount Holyoke College
   413-538-2140 South Hadley, MA 01075-6415
   fax: 413-538-2331 http://www.mtholyoke.edu/~mcrowley
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Received on Mon Nov 30 1998 - 23:36:28 NZDT

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