Re: RAID arrays and performance

["Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>]

>>> On Tue, Jan 29, 2008 at 10:45 AM, in message
<873asginrz(dot)fsf(at)stark(dot)xeocode(dot)com>, Gregory Stark <gsstark(at)mit(dot)edu> wrote: 
 
> Well consider when you've reached n-1 drives; the expected number of requests
> before you hit the 1 idle drive remaining out of n would be n requests. When
> you're at n-2 the expected number of requests before you hit either of the 
> two
> idle drives would be n/2. And so on. The last term of n/n would be the first
> i/o when all the drives are idle and you obviously only need one i/o to hit 
> an
> idle drive.
 
You're right.  Perhaps the reason more requests continue to improve
performance is that a smart controller will move across the tracks
and satisfy the pending requests in the most efficient order?
 
-Kevin