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free memory

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Eileen Millen
Trusted Contributor

free memory

On a UX11.0 K570 development server, we have several instances of Oracle Financials 11 and Cognos running. From the Perfview data, after a reboot, the memory used goes down to 25% used. We have 2Gb of memory and Oracle should take about 500Mb. The system has been up for a few weeks. When all of the instances of Oracle were shutdown, the memory used only went down to 65%. Is there an easy way to find out what is taking up all of the memory? The system has had custom patch tapes applied every 6 months. Does Oracle or Cognos have memory leaks?
Thanks Eileen
6 REPLIES
CHRIS ANORUO
Honored Contributor

Re: free memory

It takes time for the memory level to come down(rescind).
You don't have to worry, You can read about sched, vhand, lotsfree, desfree, minfree, etc. Search for HP-UX Memory Management under /docs.hp.com.
When We Seek To Discover The Best In Others, We Somehow Bring Out The Best In Ourselves.
John Poff
Honored Contributor

Re: free memory

There are a couple of things you can check. First, see what your buffer cache min and max settings are in the kernel. You can probably drop the max value down to about 10% if you are using a disk array with some buffering (EMC, etc.). Also, you might check the shared memory segments (ipcs -ma). Sometimes if Oracle does not go down cleanly it can leave some shared memory segments open. They will be marked for deletion when Oracle stops, but if there are some Oracle processes left in memory the shared memory segments won't release.

Oracle Financials can be a real memory hog. Our production box here has 12 Gb of RAM in it, so you might consider bumping up the RAM in your development box. You can talk to the DBAs about reducing the size of the Oracle SGA (I think that's the term), but they might not be able to give up much room.

If they are also running the middle tier for Oracle Finanacials on this box, take a good look at their web server. I've been able to track some of their web programs and find memory leaks in them. To do this, I used the ps -el command and tracked the process size every 10-15 minutes through the day.

eran maor
Honored Contributor

Re: free memory

Hi

i agree with john .
set the value of the dbc_max_pct to 10 ( its 10 % for the buffer cashe )

i m sending you also the pdf for handing the memory .

here is some info about the buffer cashe
dbc_max_pct
dbc_max_pct defines the maximum percentage of memory to be used by dynamic buffer cache.

Acceptable Values:
Minimum
2
Maximum
90
Default
50
Specify integer value. For more information, see Specifying Parameter Values.

Description
When the parameters bufpages and nbuf are both set to their default value of 0, the size of the buffer cache grows or shrinks dynamically, depending on competing requests for system memory.

The value of dbc_max_pct sets the maximum percentage of physical memory that can be allocated to the dynamic buffer cache.

It is possible to set both dbc_max_pct and dbc_min_pct to the same value, 12 for example, and create a kernel that uses exactly that percentage of physical memory for the buffer cache, regardless of the size of physical memory.
love computers
Eileen Millen
Trusted Contributor

Re: free memory

The dbc_max_pct is 25.
We do not have an EMC array on this system.
The disk is an OSS RAID array with only 128Mb of cache.
Eran, I am unable to open your pdf file.
Thanks for your responses.
Bill Hassell
Honored Contributor
Solution

Re: free memory

To sort all the processes by RAM usage, use this command line:

UNIX95= ps -e -o vsz=Kbytes -o pid,args=Command-Line | sort -rnk1 | more

Note: this is a single line (may be folded on this web page) and the UNIX95= ps is not a typo. It temporarily defines UNIX95 for the ps command but does not define it for any other program. Check the ps man page for other -o options.


Bill Hassell, sysadmin
Eileen Millen
Trusted Contributor

Re: free memory

Thanks Bill. This is very valuable info.
The command works and I found that
/opt/perf/bin/scopeux is taking 289.9Mb.
This is the Measureware collection.
I stopped MWA and restarted it.
It is only taking 2.9Mb now.
Would this be an indication of a memory leak,
or is this normal for MWA?

Is there an HP course that would teach really useful commands like this? Would it be covered in the Systems Internals Course, Inside the HP-UX operating system?
Thanks,
Eileen