Re: high load, no bottleneck

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

        Hello.  the worst case scenario is when a raid set is running in
degraded mode.  Greg sent me some notes on how to calculate the memory
utilization in this instance.  I'll go dig them out and send them along in
a bit.  In theory, if all your raid sets are in degraded mode at once, and
i/o is busy, you could be highly impacted, since you can have up to 40
i/o's outstanding for each raid set with my configuration option.  However,
even on machines with multiple raid5 sets, with 2 of them running in
degraded mode, I've not seen a memory bottleneck.  I don't recommend this,
of course, but somethimes stuff happens.  In any case, except for the
potential memory utilization, there's no down side to setting this number
in the kernel and not worrying about it anymore.  In fact, this is what I
do for all our machines around here regardless of whether the machine is
hosting raid1 sets, raid5 sets or a combination of the two.
-Brian