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HPUX 11.0: Paging Usage High

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LG Porter
Frequent Advisor

HPUX 11.0: Paging Usage High

Presently I have a K580 running HPUX 11.0 and Oracle database. The paging has been very high. Is there any white papers, techincal briefs, patches or addition information available to explain this problem as well as the resolution?
9 REPLIES
A. Clay Stephenson
Acclaimed Contributor

Re: HPUX 11.0: Paging Usage High

I should add that even page-outs may be normal if your application is using memory mapped files - in this case moderate page-out rates are normal.
If it ain't broke, I can fix that.
A. Clay Stephenson
Acclaimed Contributor

Re: HPUX 11.0: Paging Usage High

Search docs.hp.com for "HP-UX Kernel Tuning and Performance Guide" by Stephen Ciullo.

You need to make distinquish beyween page-outs and page-ins. Page-ins are normal and not a problem; even moderate page-out rates indicate memory pressure.

If you don't have Glance, execute vmstat and only pay attention to the 'po' column.

Typical problems are : 1) dbc_max_percent left at default 50%; on 11.0 systems in almost every case buffer caches > 400MB are useless.
2) SGA too big 3) too amny processes 4) not enough physical memory
If it ain't broke, I can fix that.
John Poff
Honored Contributor

Re: HPUX 11.0: Paging Usage High

Hi,

Are you referring to the swap usage as in 'swapinfo -tam', or are you looking at Glance and/or vmstat and seeing lots of page outs?

How much RAM do you have in your K580? How big is your swap space? How much shared memory is used by your Oracle database and what is the SGA size?

JP
John Payne_2
Honored Contributor

Re: HPUX 11.0: Paging Usage High

Everyone needs to know about performance. There is a performance and tuning guide by Stephen Cuillo at http://docs.hp.com/hpux/onlinedocs/os/11.0/tuningwp.html

He also co-authored a 'performance cookbook' with Doug Grumann, which you can find at http://h21007.www2.hp.com/dspp/files/unprotected/devresource/Docs/TechPapers/UXPerfCookBook.pdf

If you have Glance installed, Doug Grumann wrote a paper on the GlancePlus Pak at http://devresource.hp.com/devresource/Docs/TechPapers/PakPerform.pdf

Having Page In's is not necessarily bad, how much free memory does your system have? And if we are going to get into that, how much total, what is dbc_max_pct and dbc_min_pct set to?

Hope it helps

John
Spoon!!!!
Steven E. Protter
Exalted Contributor

Re: HPUX 11.0: Paging Usage High

You might also try to collect some data over time with a sar collection script. You might be seeing spikes from using gpm or other short term issues.

Set the time period in the attached script long enough so that things like archive log switches and such do not mess up your data.

It runs in background and does use a wee bit of system resources istelf.

This script is tested and a prod script in our shop.

P
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
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Founder http://newdatacloud.com
Bill Hassell
Honored Contributor
Solution

Re: HPUX 11.0: Paging Usage High

Page in refers to program starts as well as returning programs from the swap area, so ignore that value. page out are either memory mapped files or applications that have had pages written to the swap area. Excessive paging would be triple digits or higher and there are only two fixes:

1. stop running so many processes and user logins

2. Buy a lot more RAM.

Oracle needs several gigabytes of RAM to comfortably fit into memory and provide the fastest response times. Minimum RAM should be 4Gb, recommended RAM should be 6-8Gb for Oracle 64bit or multiple Oracle 32bit instances.


Bill Hassell, sysadmin
LG Porter
Frequent Advisor

Re: HPUX 11.0: Paging Usage High

John Payne: I would like to see the document that you have in your reply. I attempted to open the link however it is not available. Thanks
LG Porter
Frequent Advisor

Re: HPUX 11.0: Paging Usage High

John: That is on the document that Doug Grumman drafted on GlancePlus Pak....
Robert-Jan Goossens
Honored Contributor

Re: HPUX 11.0: Paging Usage High

I think John is refering to this doc,

Making your GlancePlus Pak perform

http://h21007.www2.hp.com/dspp/files/unprotected/PakPerform.pdf

Hope it helps,

Robert-Jan.