RE: Performance of large LF access path builds - SSD vs 10K spinny

1) This was actually a CREATE INDEX in a 3rd party supplied program. I'd like to retest setting the unit SSD parameter.
Is there a default setting I can change since I don't have the 3rd party source.

2) I think I found why R&D was faster than production. Productiion has 1.5 million deleted records, R&D had 0.

Paul

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Tuesday, September 16, 2014 7:57 AM
To: Midrange Systems Technical Discussion
Subject: RE: Performance of large LF access path builds - SSD vs 10K spinny

Also related, suppose you're an all SSD shop. And all your disks are hosted on IBM i. And that IBM i has multiple lpars it hosts (IBM i and AIX). "IF" IBM i was altered in 7.2 to automatically sense that you are running on SSD's would that auto sense pick up, even on a guested lpar, on the fact that even though the disks are hosted by another lpar that the hosting lpar is all SSD's and it should increase the thread support?
If not, if I specify UNIT SSD on the guests would it use the increased thread support? Would using the increased thread support be a bad thing because it's now guested?


Rob Berendt
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IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600 Mail to: 2505 Dekko Drive
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Ship to: Dock 108
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http://www.dekko.com





From: Sue Baker <sue.baker@xxxxxxxxxx>
To: midrange-l@xxxxxxxxxxxx
Date: 09/15/2014 07:38 PM
Subject: RE: Performance of large LF access path builds - SSD vs
10K spinny
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>



"Steinmetz, Paul" <PSteinmetz@xxxxxxxxxx> wrote on Mon, 15 Sep
2014 20:06:46 GMT:

There is no mixture of media on either LPAR, so does this
parameter have any impact.

You're correct that it doesn't seem likely to make a difference,
but it can.

When UNIT SSD is specified as part of your CREATE INDEX, more
threads will be used to complete the SQL statement than a plain
CREATE INDEX. Normally more threads means reduced runtime.
This includes when it's a 100% SSD configuration.