Re: SEQONLY(*YES nnn) recommendations on how big a block?

Somewhere I had some time trials on
5770SS1 42 HA Journal Performance

Phenomenal difference.

Again, it's an easy install and you've got 70 days to get the key to try
it out. That's probably not the legal promotional way but I think it's
one of those "honest intentions" things.

Pretty much non disruptive unless you like to reinstall PTF's just to
ensure that if any PTF's came out for it you now have the latest and
greatest. Because they sure didn't get applied to it when it was not
installed.
It's one of those confusing things "Yes IBM I am at the latest cume, hiper
and all groups. However, I've added an option since applying all those."
Just try to find somewhere in the PTF cover letter where it says that ptf
such and such was for option ## of 5770SS1. I don't think you'll have any
luck.


Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1
Group Dekko
Dept 1600
Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
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Kendallville, IN 46755
http://www.dekko.com





From: Charles Wilt <charles.wilt@xxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date: 07/14/2017 03:08 PM
Subject: Re: SEQONLY(*YES nnn) recommendations on how big a block?
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>



pretty sure those values are still valid...

On your application that writes 20M records to a journaled table, are you
using commitment control?

If not, re-read the book. :) Note that the Journal Caching PPRQ mentioned
is now a LICPGM..
5770SS1 42 HA Journal Performance

Rob has posted many times in the past that he got more improvement out of
the journal caching than going to all SSDs.

Charles


On Fri, Jul 14, 2017 at 12:40 PM, Dan <dan27649@xxxxxxxxx> wrote:

In the "General performance considerations" chapter of the redbook

Striving

for Optimal Journal Performance on DB2 Universal Database for iSeries
(SG24-6286-00), it has the following recommendation:

"Specify Sequential Only on OVRDBF
Where possible, use the CL command OVRDBF to specify sequential-only
processing when adding rows to your database tables. Also, consider

using

separate open data paths (ODPs) and open these for output when adding

large

amounts of rows to your database tables.
Also, specify the NBRRCDS parameter with a value as close to
128KB/row-width as possible to maximize memory buffer utilization."

I have tested this, especially since we turned on journaling and
performance on this one application that writes 20M records to a table,

and

found a signficant boost in performance. But I note that this redbook

was

written 15 years ago and mentions in the edition notes that "This

edition

applies to Version 5 Release 1 of OS/400". Can anyone advise whether

this

particular recommendation, specifically WRT the 128KB/row-width, still
applies today? (We're on Power 8, v7r1.) If I go with a bigger block

than

128KB, at what point do I need to be concerned with resource contention?

- Dan
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