Re: Disk IOA Placement

<snip>
 have a new 520 with two 2780 RAID controllers and am trying to find
information on whether there might be any performance gain by changing
their
placement. They shipped from the factory sitting side by side next to a
2488
IOP, but I'm wondering if they wouldn't run faster by moving one to another

2844 so they each have their own IOP. Then again maybe that would be slower

because of the extra 2844 in the mix.
</snip>

Jeff,

I almost never put two disk IOAs on one IOP.  While the IOP may have the
memory and processor to handle the load for both IOAs there is a good
chance with heavy I/O you will outrun the IOP capacity.  Since you indicate
the 2780s (and not 5709 raid enabler)  can we make the assumption these are
loaded in an 0595 tower?  The 0595 will also allow you to spread the
IOP/IOA across two busses as well.  Again, depending on I/O work load that
could be a benefit for splitting them apart.

Was there an LVT design done for your i5 520?  Even if there is not any
LPAR I always deliver an LVT design to my clients because it shows we spent
the time to consider card placement and ongoing support.  It is also a
great documentation tool for ongoing support of the server.  Any time you
want to add hardware, design it in the LVT and you have a good chance of it
being supported and working.

You may contact me off-line if you wish to discuss further.

Jim Oberholtzer
Senior Solutions Architect
Computech Resources, Inc.
Certified IBM iSeries System Expert
IBM Certification Exam SME, Implementer and Design