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Operating Systems Solaris prstat RSS memory
# 1  
Old 10-26-2010
prstat RSS memory

Hi everyone,
was hoping someone might be able to help me understand what I am seeing on one of our solaris systems.

prstat -s size -a is showing user oradba as being top virtual memory consumption.
639 oradba 3012G 2951G 100% 59:44:01 25%

why is it saying 3012G size and 2951G RSS size when there is only 28672 Megabytes of totoal memory installed in the system ?

thanks
# 2  
Old 10-26-2010
The display can be confusing
Summing memory size has no sens when it comes to shared memory , (not dedicated to a process)

Last edited by ctsgnb; 10-26-2010 at 09:45 PM..
# 3  
Old 10-26-2010
thanks ctsgnb for the reply

do you have any advice on how to better understand memory usage when dealing with shared memory ?
# 4  
Old 10-26-2010
About solaris memory management, you can read whatever has been written by Richard Mc Dougall.
About Oracle memory management, you can read whatever has been written by a member of tha "oak table" (Tom Kyte, Jonathan Lewis, Tanel Poder...)
Still regarding oracle : read about PGA automatic Tuning (from 9i i guess) as well as SGA automatique Tuning (from 10g i guess) (get info about how to set parameters sga_target, pga_aggregate_target, workarea_policy...)
Read also the concept guide Oracle as well as the Oracle Tuning guide of the version you are running.
make sur you have not exceeded the number of process/sessions (see gv$resource_limit view)
make your your system is correctly sized (semmns semmni etc... solaris parameter should be sized accordingly with the oracle instance it hosts (see Oracle Recommandation).
If you run Oracle in a local zone on solaris 10 then make sure you have a very recent patch update (Solaris 10 (8/07)) because the proc_lock_memory privilege (check with ppriv -v <pid>) has been added by default in the non-global zone so you can take advantage of the dism (Dynamic Intimate Shared Memory).

Last edited by ctsgnb; 10-26-2010 at 10:51 PM..
# 5  
Old 10-26-2010
SunOS 5.9 sun4u sparc and Oracle 10.2.0.4
# 6  
Old 10-26-2010
on oracle 10 you can also run the usefull AWR report which can almost automagically generate an HTML report at a chosen time windows and will show you many use infos about the load of your system (memory consumtion, heavy sql statement, lock, latch, ...)
# 7  
Old 10-26-2010
thanks for all that info ctsgnb your time and effort is very much appreciated !! i will look further into what you have recommened.
thanks, k

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