running out of virtual memory

[kholikt]

Hi,

I have a server with Oracle application server running. A couple of times we found that the process was hanged. The complain from the application log was "running out of virutal memory".

The strange thing is our swaps were hardly used.
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 3788800 0 3788800 0% 0 - 1 /dev/vg00/lvol2
dev 1048576 0 1048576 0% 0 - 1 /dev/vg00/lvol3
dev 3145728 0 3145728 0% 0 - 1 /dev/vg01/lvol1
reserve - 909972 -909972
memory 1772592 744012 1028580 42%
total 9755696 1653984 8101712 17% - 0 -

It seems like the application was only allocated certain amount of virtual memory. Is there any kernel parameter that we can change or this has to be done in the application level?

[Alexander M. Ermes]

Hi there.
You should check the usage of the ORACLE SGA.
Perhaps you should enhance the shared_pool_size, the sort_area_size and the sort_area_reained_size depending how much much RAM you have and whether you run 32-bit or 64-bit. The background processes of the application eat up a lot of this ( Concurrent manager processes ). Perhaps you can reduce the number of processes for the ConcMgr as well.
If you need more help, you can contact me at
Alexander_Ermes@web.de

Rgds
Alexander M. Ermes

[Darrel Louis]

Hi,

Kernel parameters to check:
dbc_max_pct; dbc_min_pct; nbuf; bufpages; maxssiz; maxdsiz.

Do a search on Oracle and these Kernel parameters and you'll find a number of treaths regarding virtual Memory, in the forum.

also read the following:
http://www.docs.hp.com//hpux/onlinedocs/os/KCparams.OverviewAll.html

regards

Darrel

[CHRIS_ANORUO]

Hi Kholikt,

Have a look at the attached Kernel parameter for my Oracle Production servers on K580 10.20.
If your SGA's are big, reduce them and retune the kernel in line with this attachment for a start

[Bruce Regittko_1]

Hi,

Is pseudo swap enabled? If not, you could have a situation where there is not enough vm to reserve even though swap is not actually used. Check to see if the kernel parameter swapmem_on is set to 1. If not, pseudo swap is not enabled.

--Bruce

[Mladen Despic]

Hi!

I had a software support call open with HP concerning some memory issues on our Sybase server. HP had the information that Oracle does not recommend enabling pseudo-swap on their database server. Further discussion with Sybase Technical Support confirmed the same. According to their sources, pseudo-swap may affect any application configured to use large amounts of locked memory.
Therefore I would recommend disabling pseudo-swap on your system, i.e., change swapmem_on=1 to swapmem_on=0 in SAM - even if it doesn't help your problem :)

HTH