Oracle Database Discussions

Just SGA and PGA, if you had some problem with the memory you should look for the kernel parameters and the alert.log as well as the trace files this alert.log may point to.

If you are planning to grow your instance by means of growing the sga memory subregions, you should first consider if you have enough capacity to grow.

One more thing, it is important to specify which Oracle version you are talking about, in 10g the memory is seized differently than on older releases.

~ Madrid
http://hrivera99.blogspot.com

The main parameters are pga_aggregate_target, sga_target, sga_max_size. This memory normally does not increase in size when the database is running, unless you have a bug or memory leak.

Each session/process will also use some memory, so you should check how many sessions were connected.

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I would recommend identifying your total memory req's and go for sga_target and pga_aggregate_target.
What are the errors in your alert.log?

Is there any errors reported in alert log or any kind of trace file generated before crash.
Depending on the issue (error) you need to take action ( increase the parameter values). If this is issue with application that you running on database, Whatever value you set it will have issue some point in time.

hi,
while installing oracle on server what is the shmmax parameter value used if you give large amount then there will be paging b/n ram and swap space.

check that out

If you are on 10g or later and have the license to use AWR you could use the DBA_HIST_PGASTAT view to check if any excessive PGA allocation took place in the past. This could be caused e.g. by PL/SQL or Java code that allocates large chunks of memory, in PL/SQL typically caused by in-memory collections. Oracle might not be able to honor the PGA_AGGREGATE_TARGET value set if such things happen in PL/SQL or Java and you'll see that in DBA_HIST_PGASTAT in the "over allocation count" and the "maximum PGA allocated" statistics.

In Pre-10g databases you can only monitor the current PGA statistics by querying V$PGASTAT, which means that the statistics from before the crash are lost as the instance re-start reset the V$PGASTAT statistics.

Regards,
Randolf

Oracle related stuff blog:
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SQLTools++ for Oracle:
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