topic Re: swapinfo shows memory erosion? in Operating System - HP-UX

swapinfo shows memory erosion?

Gary_O — Tue, 20 Jul 2010 15:23:12 GMT

Hello all,
I have an L Class 9000 Server, OS is PA-RISC
HPUX 11.11
I have 1.5 GB of memory, and current swap/dump space defined as 1 GB i.e. (lvol2)

I am also running Oracle 10gR2.

I am seeing a steady erosion of my swap/memory space...

Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1048576 0 1048576 0% 0 - 1 /dev/vg00/lvol2
reserve - 545488 -545488
memory 1129284 725592 403692 64%
#
#
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1048576 62668 985908 6% 0 - 1 /dev/vg00/lvol2
reserve - 480936 -480936
memory 1129284 832032 297252 74%

I ran the procsize tool and didn't see anything unusual..
oracle takes up a lot, but it doesn't seem to be increasing...

Thanks for any ideas.

Re: swapinfo shows memory erosion?

Steven E. Protter — Tue, 20 Jul 2010 15:31:04 GMT

Shalom,

This could be due to normal processing.

Try this tool:

http://www.hpux.ws/?p=8

It tracks memory use over time, you set the parameters and collect the data.

The Memory Leak Detector.

SEP

Re: swapinfo shows memory erosion?

John Guster — Tue, 20 Jul 2010 16:55:20 GMT

You may have performance issue due to device swap. If it is possible, add more device swap to 2 x size of RAM, i.e add 2GB more to swap. Good Luck.

Re: swapinfo shows memory erosion?

Bill Hassell — Tue, 20 Jul 2010 17:17:53 GMT

This isn't an HP-UX issue. If a program wants more memory, it asks for it. If it has asked for more memory than you expect, contact the manufacturer (Oracle?) of the program and have them address the condition. Additionally, memory mapped files (used by your applications) will use a portion of the swap space.

The only time to be concerned is when swap space becomes heavily used (more than 40%-50%) and it doesn't stop increasing, or performance is awful *AND* vmstat reports po (page out) rates more than 50-100. Then you have three choices:

- Stop running so many processes or user applications on this system,

- Get the DB or applications patched (if available)

- Buy more memory.

FYI, 1.5GB of RAM is pitifully small for reasonable performance with Oracle. I would run a minimum of 4GB, perhaps 6GB to 12GB for best performance on a midsized computer like the L-class.

Re: swapinfo shows memory erosion?

Gary_O — Tue, 20 Jul 2010 18:34:49 GMT

Thanks guys,
I am not seeing any page outs (po).

# vmstat 10 10
procs memory page
faults cpu
r b w avm free re at pi po fr de sr in
sy cs us sy id
1 0 0 98860 6353 36 8 0 0 0 0 0 551
789 89 1 1 98
1 0 0 82281 6297 36 6 0 0 0 0 0 608
769 89 0 1 99
1 0 0 100778 6297 29 4 0 0 0 0 0 646
637 86 0 1 99
1 0 0 99976 6297 37 5 0 0 0 0 0 662
741 90 0 1 99
1 0 0 81577 6297 37 5 0 0 0 0 0 644
736 90 0 1 99
1 0 0 98338 6297 37 5 0 0 0 0 0 647
771 88 0 1 99
1 0 0 98240 6297 37 5 0 0 0 0 0 661
726 85 0 1 99
1 0 0 84669 6297 33 4 0 0 0 0 0 664
757 88 1 1 99
1 0 0 105058 6297 37 5 0 0 0 0 0 491
754 87 0 1 99
1 0 0 105247 5964 50 5 6 0 0 0 0 467
1016 97 1 1 98

Since my ram is 1.5gb and my current
swap/dump (lvol2) is 1gb, is it a good idea to increase my swap/dump to 2gb?

Re: swapinfo shows memory erosion?

Dennis Handly — Tue, 20 Jul 2010 21:25:29 GMT

It would be helpful if you provided "swapinfo -tam" to get the totals, instead of the default.

If you want to see which process is taking more memory, you can use top and look at the SIZE column.

Does it get as far as running out of memory at 100%?

Re: swapinfo shows memory erosion?

muruganantham raju — Wed, 21 Jul 2010 03:00:32 GMT

Hello,
You don't have to increase your device swap which is 1GB at present. swapinfo command output shows that only 6% of your device swap is being utilized. This means there is no real constraint in device swap space.
What ever said and done, 1.5 GB memory is too meagre for Oracle 10g. Please upgrade RAM to 3-4GB. This only provides better performance.
Regards,
Muru

Re: swapinfo shows memory erosion?

Dennis Handly — Wed, 21 Jul 2010 05:25:08 GMT

>Muru: swapinfo command output shows that only 6% of your device swap is being utilized.

It also shows that 45% is reserved.

(But if -tam was used, we wouldn't have to resort to a calculator.)

Re: swapinfo shows memory erosion?

Gary_O — Wed, 21 Jul 2010 15:22:15 GMT

Here are the current totals:

# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1024 61 963 6% 0 - 1 /dev/vg00/lvol2
reserve - 468 -468
memory 1103 807 296 73%
total 2127 1336 791 63% - 0 -

Thanks,
Gary

Re: swapinfo shows memory erosion?

Prashanth.D.S — Wed, 21 Jul 2010 16:49:44 GMT

Gary,

Performance analysis is a tough job, in order to understand who/what is consuming memory you may need tools like kmeminfo which can be supplied by HP only.

I would suggest you to involve HP to address this issue.

NOTE: I have noticed on many occations applcation (in your case Oracle) to be the main cause of high memory consumption, you may involve Oracle aswell..

Best Regards,
Prashanth