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Swapping is killing production Oracle database

Stephen Riddle
Occasional Visitor

Swapping is killing production Oracle database

Please help me. I just inherited this system, and it is, for all intensive purposes, down. Attached are the kernel parameters, vmstat output, swapinfo output and top output. They were all taken at the same time. Please help.
7 REPLIES
Stephen Riddle
Occasional Visitor

Re: Swapping is killing production Oracle database

Sorry, I've been at work for over 60 hours. The system is an N-class with 4 440 Mhz processors, 4 GB RAM and 4 GB of swap. Thank you in advance.
Stephen Riddle
Occasional Visitor

Re: Swapping is killing production Oracle database

 
Curtis Larson_1
Valued Contributor

Re: Swapping is killing production Oracle database

well with vxfsd, syncer, swapper, lvmkd, vhand, etc all at < 1% swapping isn't your problem. I doubt if any I/O is being done at all.

with the 3 processes oraclefinprd running at 99.9% user cpu. I'd guess they are stuck in a very tight loop.
Bill Hassell
Honored Contributor

Re: Swapping is killing production Oracle database

AS mentioned, it doesn't look like a memory pressure problem at all. The oracle processes are consuming 100% of the cpu which is most likely what they were told to do. It's rather easy to design SQL queries that consume huge amounts of CPU time. Whether that is what was intended is something for the DBA to decide.

Assuming the system is reasonably patched (swlist -l bundle) with patch bundles from 2001. Selective patching can introduce some idiosyncrasies. But I think knowledgeable Oracle changes will do far more to solve the problem than any kernel tweaking.


Bill Hassell, sysadmin
Roger Baptiste
Honored Contributor

Re: Swapping is killing production Oracle database

hi,

The stats you showed do not indicate a swap load on the system. for eg: swapinfo shows enough free swap space. It seems there are three oracle processes hogging CPU load and that can slow down the system. These processes could be Valid ones or they could be poorly written sql scripts. Check with the DBA on what those three processes (sitting on top of top) doing.

Use glance tool to gain more info on the usage of the system. glance is more reliable and exhaustive than top .

HTH
raj
Take it easy.
Dennis J Robinson
Frequent Advisor

Re: Swapping is killing production Oracle database

Looks like you where showing large amount of CPU utilization out of Oracle.

Oracle dba's can reduce CPU utilization even out of processes which do not do physical I/O's by minimizing the amount of logical I/O's they do.

Queries need to be optized to minimize cpu resources.

You know the drill