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Re: New Power8 Disk Perf Issues



fixed

CEC with 0 cache could be used for VIOS, if you're hosting all storage in
the SAN, there is very litle I/O from VIOS to its rootvg...
I just came back from a client where somebody sold a solution where VIOS
lives in 2 mirrored SSDs and IBM i was supposed to live in 6 spinnys served
by VIOS... They gave up when performance wasnt even near what it should be
and got a v7000...


On Tue, Aug 26, 2014 at 12:13 PM, Steinmetz, Paul <PSteinmetz@xxxxxxxxxx>
wrote:

Why would you pick a backplane option with 0 write cache.
History has proven that the CEC with 0 write cache will be a performance
issue.
History also has shown that the CEC should be avoided for a production
lpar.

Paul

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of
Jim Oberholtzer
Sent: Tuesday, August 26, 2014 11:10 AM
To: 'Midrange Systems Technical Discussion'
Subject: RE: New Power8 Disk Perf Issues

Thanks for the clarification Sue. The literature is not clear on those
point.

--
Jim Oberholtzer
Chief Technical Architect
Agile Technology Architects


-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of
Sue Baker
Sent: Tuesday, August 26, 2014 9:44 AM
To: midrange-l@xxxxxxxxxxxx
Subject: RE: New Power8 Disk Perf Issues

"Jim Oberholtzer" <midrangel@xxxxxxxxxxxxxxxxx> wrote on Mon, 25 Aug 2014
18:24:28 GMT:

We know that P8 will use internal storage, except, as I understand it,
if you have the back plane split so you can run dual VIO Servers.

No, the split backplane is supported by IBM i so you do not have to run
dual VIO servers. This means you could have VIOS for NPIV using 1/2 the
disk bays. Then sitting right beside an IBM i LPAR using the other 1/2 of
the disk bays.

Then you must use external storage.

Even if you do dual VIOS, there are card slots for disk IOAs which can be
dedicated to an IBM i LPAR. I'm not sure why you say with split backplane
storage must be external SAN. Unless you really meant storage will be
external to the CEC.

So
it's about half right. Even then I think you might get away with
internal storage but it would be A) slow and B) very limiting so
certainly not recommended.




--
Sue
IBM Americas Advanced Technical Sales Support (ATS) Power Systems
Rochester, MN
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