topic Re: high swap utilisation in Operating System - HP-UX

high swap utilisation

bijoy k — Tue, 24 Mar 2009 11:01:16 GMT

Hi Guys ,

This thread is for a high swap utilisation in one of our server. As of now , there is no impact in the server.But need to know the reason behind this high swap utilisation.

# swapinfo -tm
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 2560 1556 1004 61% 0 - 1 /dev/vg00/lvol2
dev 500 500 0 100% 0 - 1 /dev/vg00/lvol9
reserve - 1004 -1004
memory 2077 1699 378 82%
total 5137 4759 378 93% - 0 -

Do I need to add additional swap logical volumes for this , will that going to recover from this situation ?

Expecting valuable advise from you guys...

Many Thanks in Advance ...

Bijoy

Re: high swap utilisation

bijoy k — Tue, 24 Mar 2009 11:10:30 GMT

Hi Guys,

In addition to the above , pasting the output of print_manifest on the Physical memory and swap configuration.

System Hardware

Model: 9000/800/D390
Main Memory: 2816 MB
Processors: 2
OS mode: 64 bit
HW capability: 32 or 64 bit
LAN hardware ID: 0x080009AF6DFC
LAN hardware ID: 0x00306E0F00B3
Software ID: 2013620986
Keyboard Language: Not_Applicable

Swap configuration

type size priority device/location
dev 2560 1 /dev/vg00/lvol2
dev 500 1 /dev/vg00/lvol9

Thanks and Best Regards..

Bijoy

Re: high swap utilisation

john123 — Tue, 24 Mar 2009 13:59:31 GMT

Hi Bijoy,

Whats ur buffer cache util ?
What does ipcs -am shows ? any orphaned SGAs ?
try using UNIX95= ps -e -o "user,vsz,pid,ppid,args" | awk 'NR>1' | sort -rnk2 |more
to find if any process running hot

Regards
John

Re: high swap utilisation

Ganesan R — Tue, 24 Mar 2009 14:08:15 GMT

Hi Bijoy,

Whenever a new process starts, it will reserve some space on swap for future use. If at all that needs swap space then those reserved space will be used. That way only swap space will be occupied.

If you really want to know the swapping activity, use vmstat command and look at the values pi and po. This will provide the page in and page out activities. If page in and page out activity happens, it means it is physical memory bottleneck. You should consider to increase the physical memory.

Re: high swap utilisation

Ganesan R — Tue, 24 Mar 2009 14:11:36 GMT

Hi Bijay,

See this thread to know more about swap space utilisation.

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1288219

Re: high swap utilisation

Dennis Handly — Tue, 24 Mar 2009 14:54:34 GMT

>Do I need to add additional swap logical volumes for this

Do you expect to add more applications/users?
Are you running into out of memory errors?

Re: high swap utilisation

Steven E. Protter — Tue, 24 Mar 2009 16:10:04 GMT

Shalom,

If you are getting out of memory areas the short term solution is to add swap.

However this will not improve performance and might even make it worse. The long term answer is to purchase and add memory to the system. Decreasing memory demand is an option but I have yet to succeed when I propose that.

SEP

Re: high swap utilisation

Avinash20 — Tue, 24 Mar 2009 18:12:13 GMT

Phyiscal memory: 2816 MB

Swapping is high which is a bad sign

PCT USED:
/dev/vg00/lvol9: 100%
/dev/vg00/lvol2: 61%

Reserve swap : 1004 MB

Device swapping might imply to page-outs which are taking place in your server

vmstat will be showing lot of page-out(po)
# vmstat 1 1

1. Increasing the swap is not a permanent solution
2. You need to find out why the physical memory is getting exhausted.
May be you need to tune the application, or reduce the load or increase the physical memory on the server.

Re: high swap utilisation

TTr — Tue, 24 Mar 2009 18:56:33 GMT

The max memory for the D390 is 3GB (3072MB). You only have room to add another 256MB and based on the current installed memory, you would have to remove the 256MB module so that you can add the last 512MB module.

You already have 2.5GB of code swapped out to the two swap volumes (500MB + 1556MB), so adding memory will help but not eliminate you disk swapping. If the stuff that is swapped out already is idle you may be ok, otherwise if it is active, your server will be extremely slow to almost unusable. You need to clean all unnecessary processes to conserver memory.

Re: high swap utilisation

Dennis Handly — Tue, 24 Mar 2009 22:38:28 GMT

>TTr: You already have 2.5GB of code swapped out

Since code isn't swapped out, you probably meant "data". :-)