Re: Large systems and full disks

We have a 3.1TB Domino server and it really started slowing down as it inched closer to 90%. It was not 3.1TB when it was hitting 90%, at that time
it was still "only" a 2.4TB Domino server. So relatively speaking you may notice performance impact at 90% or above. We had another i machine that
hit 94% and was still humming along until it started griping about storage for some job that went haywire, it's threshold was/is 95%. That small
server "only" has 960GB of storage but it has 30xinternal disks and 19xSAN disks. So if you have a bunch of "arms" then you may not notice the
impact. The Domino server has less "arms" than the smaller server which is probably why it was affected more easily. I used the term "arms" versus
arms because of the SAN impact of luns versus arms. Lot's of "arms" or luns on the same physical disks will not yield better performance because
you're still stuck with the same physical arms of those SAN disks under the covers. We figured out that little performance bottleneck when I started
this job. Then we spread out those luns over more disk packs, instead of the one REALLY big disk pack like it was previously configured.

Good luck,
Bill Epperson Jr.
Systems Communications Analyst
Memorial Health System
(719) 365-8831





Lukas Beeler <lukas.beeler@xxxxxxxxxxxxxxxx>

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On Thu, May 28, 2009 at 20:12, <franz400@xxxxxxxxxxxx> wrote:

On a large system with over 1,000 gig

Interesting perspective ;)

1TB can be had in 4 arm configuration - which would really, really
slow if you actually used all that space.

Basically, you need to keep storage utilization low - on a 1TB system
with 90% utilization, you will not have enough arms to keep the speed
okay. So, the more capacity the system has, the less you can actually
use.

Usually, it's the best idea to go with with the smallest but fastest
drives you can get - for the newly launched Power 6 rehash, that would
be the 32GB SSD.

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