topic Re: 6GB Memory become full in Operating System - OpenVMS

6GB Memory become full

Mahmoud_1 — Tue, 29 Nov 2005 05:23:56 GMT

Dear all,
I have alpha server 8200 with OpenVMS version 7.3-1 running Oracle RDB/Cobol and Oracle RDBMS 8i. We upgraded the OS to 7.3-2 and the Oracle RDBMS to 9.2.0.5 and we increased the memory from 2GB to 6GB after that we notesed that the memory become 99% used and the system become loaded and many of the proceses become swapped out.
Note : no thing made to the applications for both RDB & RDBMS, no thing changed for the accounts or sysgen params.
are there any thing to check or do.
This is a critical system.
Regards

Re: 6GB Memory become full

Kris Clippeleyr — Tue, 29 Nov 2005 05:34:51 GMT

Mahmoud,
First things to look at is SHOW SYSTEM (look for memory hogs in the "Pages" column), SHOW MEMORY (of course) and execute
@SYS$UPDATE:AUTOGEN SAVPARAMS TESTFILES CHECK_FEEDBACK to see what alterations you might have to do to the system paramaters.
Regards,
Kris (aka Qkcl)

Re: 6GB Memory become full

Jan van den Ende — Tue, 29 Nov 2005 05:44:03 GMT

Mahmoud,

maybe you already did, but just to make sure:
Oracle has guidelines for things to change when you go from V8x to V9x.
Several of those will deal with SYSGEN params. Be sure to apply them!

Then run for at least 24 hours, with a representative load, and execute AUTOGEN as Kris wrote.

Success.

Proost.

Have one on me.

jpe

Re: 6GB Memory become full

Marc Van den Broeck — Tue, 29 Nov 2005 06:16:53 GMT

Mahmoud,

are you using reserved memory for your Oracle instance?
And if yes, how large is it?

Rgds
Marc

Re: 6GB Memory become full

Mahmoud_1 — Tue, 29 Nov 2005 06:49:30 GMT

Dear Marc,
Yes we have reserved memory 2.5GB
Regards

Re: 6GB Memory become full

Marc Van den Broeck — Tue, 29 Nov 2005 08:29:02 GMT

Mahmoud,

So you are using more reserved memory then you did in previous version. And you thus have 3.5 Gb left for system.
Can you check how many Oracle 'user' processes there are? (process name should start with ora). You will find the background processes and some server processes.
Now, using almost all memory is not really bad, but if many processes are outswapped then it might not be ok.

Autogen might help you, but i guess you have to find out what is using lots of memory that was not there in previous install.

Rgds
Marc

Re: 6GB Memory become full

Ian Miller. — Tue, 29 Nov 2005 08:31:32 GMT

several PQL_M and PQL_D parameters esp PQL_DWSEXTENT, PQL_MWSEXTENT increased a lot in V7.3-2. This will allow a process to use a lot more memory than before. You may wish to check that specific quotas are being specified for detached processes. Check also BORROWLIM, GROWLIM

Re: 6GB Memory become full

Jan van den Ende — Tue, 29 Nov 2005 08:59:24 GMT

Mahmoud,

Under 7.3-2, as soon as there has been any decent amount of memory been used, the _FREE_ memory is held "occupied" by the XFC cache. So, very soon your memory will _LOOK_ fully used.

$ SHOW MEMO/CACH

begins with "Allocated"

You can add that amount to your Free memory, as the cache will free it the moment there is demand.

hth

Proost.

Have one on me.

jpe

Re: 6GB Memory become full

Hein van den Heuvel — Tue, 29 Nov 2005 10:15:32 GMT

Before you had 'only' 2GB, so your SGA for Oracle/Oracle must have been well under 2GB, maybe 500MB?

Now you have more physical memory and you have set aside 2G reserved memory for Oracle. One assumes you also changed the Oracle SGA params in init.ora to exploit this new found memory.

Did you make sur the new, larger sga is actually using the reserved memory and not 'double dipping' by having it reserved but allocating from normal memory?

fwiw,
Hein.

Re: 6GB Memory become full

Mahmoud_1 — Thu, 01 Dec 2005 04:27:36 GMT

Dear All,
Thanks for help,
I checked all what you asked me for, I will upload a text file with some information about the users,memory, oracle account, sysgen params, one of the users account.
best regards.
Mahmoud

Re: 6GB Memory become full

Hein van den Heuvel — Fri, 02 Dec 2005 12:58:32 GMT

Thanks for the details.

A few observations...

The XFC cache is holding on the 2.2GB (35%) of the memory. This is 'soft' allocationn. That is, if there is other memory pressure, then it will release memory there.

The "Memory Reservations" for ORA_A73_SGA hold 2.44GB, for 40% of the memory. Less than 1/2 of that is actually used (149669 out of 320000). The unused 1.6GB (roughly) is not available to anything else. You should work with the DBA's to grow the SG to use the memory set aside, or reduce that memory set aside.

So while VMS reports 0 free, you really have more than 3GB free-able right now!

Hein.

Re: 6GB Memory become full

Emad Omar — Wed, 07 Dec 2005 05:40:08 GMT

Hi all,

I have a similar case at one of our customer. During normal backup procedure I noticed that Memory capacity occupied about 99% and it does not releaded until next reboot.
So please give me your opinion about this and if there is any settings or enhancements for releasing the Memory occupation.

Regards,

Emad Omar

Re: 6GB Memory become full

Hein van den Heuvel — Wed, 07 Dec 2005 11:29:44 GMT

Emad, thanks for lookign around and finding an appropriate topic. Great. Now carefully read the information presented above and see if it applies. If it does... you ar eall set.

If it does not, start your won topic. Point it back to this and explain why it does not apply. Gather the kind of infomation requested above and be sure to attach or include it to that new topic.

Good luck!
Hein.