Just to chime in -

We run with 2 spares per filer. That is for all our filers, from F840's/12 shelves/36gb drives, F760's/6 shelves/36 gb drives and F760/8 shelves/18gb drives. Since spares are per filer, not volume, the main thing we wanted to avoid was volume failure, which would occur if 2 drives in RAID group failed at the same time. That has never happened, although we almost hit that after moving a filer and 2 disks had a hard time spinning up. We also have 2 because the filers are remote from our offices, so the "insurance" or piece-of-mind are worth it to us.

--sam

-----Original Message----- From: Tom Yergeau [mailto:yergeau@yergeau.net] Sent: Wednesday, August 07, 2002 1:20 PM To: toasters@mathworks.com Subject: RE: # of volumes

I generally liked to keep one spare per 14 drives. Since spares are global and can be used by any volume having a "x spares per volume" didn't make sense to me, so I figured out how many drives I was comfortable with having one spare for, and arbitrarily decided on 14.

Mad Dog