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Inactive Memory

Inactive Memory

Hi,
I have a DS20 box running Tru64 5.1 with PK4.The database running on this box is Oracle 8.1.7 and Oracle application 11.5.3.The problem we are facing is that occasionally (or always) whenever a second database is started a large chunk of memory goes into inactive mode (collect ???s cm ) and never returns to active until database is brought down OR server is rebooted. System keeps on running with low memory and sometimes just hangs.
Is there any kernel parameters need to be tuned for this?
I will appreciate all the replies.
Thanks.
Ashish
The best way to make dreams true is to wake up.
3 REPLIES
Paul Sperry
Honored Contributor

Re: Inactive Memory

Dave Bechtold
Respected Contributor

Re: Inactive Memory

Hello,

The previous reference to the Performance and Tuning Guide is helpful to understand InActive Memory, memory not used recently and available to potentially be used for FreeList.

This could be an issue with how the database is tuned for memory usage, grabbing a larger than required amount of memory?

Having a large amount of InActive memory is not necessarily bad, but not optimal. In some circumstances may be desired depending on the application or application mix. When free memory drops to a certain level, the UBC LRU and then the InactiveList (InActive memory) are candidates for free pages. If the pages are dirty then they are flushed before being freed.

I'd be watching Free Memory List, if it's dropping and causing memory to be reclaimed from the InActive memory, then review UBC parameters (ubc_maxpercent - consider dropping to ~70% from 100 maybe). I'd really look into the database application and see if it is optimally configured for its required memory.

Hope this help,
Dave Bechtold

Re: Inactive Memory

Thanks.
In our case the application is Oracle Application and memory doesn't goto Inactive mode when only one database is up but as soon as second database is brought up the moemory starts to goto to inactive pool and the only way to free it up from inactive pool is to bring down the application.
My DBA is asking me why the server doesn't swap when the free memory reachees the low limits and why it goes to Inactive mode?
The best way to make dreams true is to wake up.