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Defragment Memory on HP N-Class running HP-UX 11 / Oracle 9

Posted on 2004-04-02
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Last Modified: 2013-12-06
Does anyone know how I can defragment physical memory on an N-class running HP-UX 11.0 ?
When I start oracle, I get an error about not enough contiguous memory, and I believe that other processes are coredumping without deallocating memory.
I need to clear up the "memory leaks" and defrag what is in use.
Any ideas?
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Question by:simpsop
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6 Comments
 
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by:jlevie
ID: 10745469
Does this happen right after a reboot? If it does it might indicate that there's insufficient physical memory in the machine.
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by:tfewster
ID: 10746007
If a process dies & coredumps, HP-UX will clean up after it.  To be honest, I've never heard of "contiguous" memory and I can't see the advantage as all in-memory I/O operations are virtually instantaneous.

Expanding on jlevies post:
Check physical memory with `dmesg |grep Physical`; The system may have disabled a bank of memory if it has persistant faults. Remember that a pecentage of Physical memory is reserved for the operating system, plus a percentage for disk caching - But the dmesg output should show you the "usable" amount.
Check the allocated swap with `swapinfo`. Though you don't really want the system to be paging/swapping oracle processes as performance will nose-dive...
Check the Oracle SGA (shared memory config) which grabs a chunk of memory as the DB starts up. If it is trying to grab more memory than is available, HP-UX would allow it but  Oracle may well complain...
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gheist earned 500 total points
ID: 10747081
Maybe some app does not release shared memory segment(when crashing), check out ipcs -m, and remove unreferenced segments with ipcrm -m ID

Oracle allocates SGA residing in RAM, which may be more than your system has or permits in user specific limit config
(check out ulimit -a or limit)
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by:chris_calabrese
ID: 10757190
Modern systems do not have the concept of 'contiguous' physical memory, since each process sees only its virtual memory space as mapped to physical memory through the MMU. More likely, jlevie is correct that there isn't enough physical memory on the system to support the Oracle install.
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by:tfewster
ID: 10760790
I did a bit of searching after I sobered up, and Oracle still requires contiguous memory within the Shared memory area - See http://www.databasejournal.com/features/oracle/article.php/2195001  - Which tends to back up gheists tip on tidying up Shared memory & the others comments about physical memory
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by:gheist
ID: 10765948
and make sure SGA size in ora.ini is smaller than locked size, data size or system memory
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