we have a database server with not much load and two good processors (4 core) on AIX 6.1. The Oracle becomes slow some time, but not all the time. I suspect the server is memory constraints. In order to justify the memory upgrade I am trying to see how much memory is being used by each process. When I look at following OS command results I am wondering where all the memory goes.
ps aux command gives account for only 46% of memory usage. Topas says 94% memory usage and vmstat says no paging. I am not an SA, what should I conclude from following.
Thanks,
following is the output of ipcs. Topas still shows 95% comp memory usage.
Code:
/home/oracle> ipcs -mb
IPC status from /dev/mem as of Mon Sep 19 12:59:55 EDT 2011
T ID KEY MODE OWNER GROUP SEGSZ
Shared Memory:
m 1048576 0x7800002c --rw-rw-rw- root system 268435456
m 2097153 0x78000020 --rw-rw-rw- root system 16777216
m 1048578 0x4f1f16e0 --rw-r----- oracle dba 612376576
m 3 0x21002007 --rw------- pconsole system 10485760
m 4 0x0d0009a0 --rw-rw---- root system 1440
m 5 0x2100200d --rw-rw---- root system 52428800
Last edited by Scott; 09-19-2011 at 05:01 PM..
Reason: Added code tags
Despite the fact that your data is very apparently taken while nothing was happening on the DB rather than when you were facing your issues, I can still tell you that you actually use 1 GB memory computational that you do not have - do lsps -a and you will see a significant amount of paging space used - most likely AIX has moved parts of your DB entirely to disk - BAD THING
your box is hopelessly overutilized. How much memory oracle is really using is something you can see with svmon -U oracle
Please note as well that the system needs memory for filesystem buffering, for any kind of connection, for each oracle process .... this adds up - and the memory you have assigned to your SGA / PGA is not available in first instance.
User Inuse Pin Pgsp Virtual
oracle 90121 10167 162819 224644
the number under pgsp is what is actually in paging space and owned by oracle - close to 2/3 of your entire oracle memory utilization - no wonder that your DB is slow
if AIX has moved enough into paging space to have sufficient memory to operate than you will not see any 'new' paging - page ins / page outs - until you start a very work intensive process. The system will at that moment probably start extensive scan and free until it gives up and just moves more content into paging.
From the data you have posted so far, the system is running apart from oracle websphere too - as far as I remember you assign memory to websphere too similar to SGA + PGA to oracle - this is physical memory not available any more to the system.
As your oracle memory utilization seems decent, I would assume that websphere is consuming a large chunk of memory for itself.
Can you maybe post the output of svmon -U appuser too ?
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09-19-2011
