Re: 520 Config

10 modern disks with a modern controller can outperform 23 older disks,
especially on older controllers. When we went from a 730 to a 570, we took
the box from 63 arms to an LPAR with 18, and later to 12 disks and still had
better disk throughput. Of course the disks went from 10K to 15K and the
controllers went from something like 4 or 8MB of cache to a GB. The cache
probably made the biggest difference.

That said, unless you're going to be doing guest LPARs in the future, you
may want to keep some extra disks around. You should have your BP do
planning with estimates for the LPARs you think you'll want in order to
avoid any gotchas when you try to create them.

And yes, WebSphere App Server is a RAM pig.

On Tue, Sep 1, 2009 at 11:25 AM, Mike Cunningham <mike.cunningham@xxxxxxx>wrote:

We are looking to upgrade our 520 and our business partner has proposed
this config
2 CPUS 8300 CPW
32GB RAM
10 - 139.5GB disk drives

We currently run 1 CPU, 16GB RAM and 23 drives of various sizes.

I know this is a hard question to answer without a whole lot more
information but, generally, wouldn't going from 23 arms to 10 create a
bottleneck at disk IO? If we have any bottleneck currently it is with RAM
(Websphere takes a lot) and an occasional spike in CPU. We wanted to get
dual CPUs because we do plan on doing some partitioning in the future. I
know this config was done using IBMs configuration tool, would it build a
system that was not going to perform well?
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