Hi, I am having 4GB of RAM on RS

[akam25]

Hi,
I am having 4GB of RAM on RS6000 running AIX5.1L. I am having 3 oracle databases running as well as a java rmi application which uses tomcat and apache.

I didn't notice earlier but yesterday I saw using nmon(utility to monitor memory and cpu performance) that it is having 99% to 100% physical memory utilization and 7% virtual memory utilized. I was worried about the crash and shutdown the oracle databases, oracle agents and listener plus the java application. Even then it releases only 5% memory. Can somebody suggest me how can I check the leakage or is it a normal process. Top process only using 5M of space.

One of my collegue told me that it is normal as in unix systems it tries to utilize as much memory as possible and do not worry until virtual memory of 50% gets used. Is it true.

Please help me what can be done.

Thanks,
Aj

 

[ProbablyDown]

Just make sure your Oracle DB sga size doesn't exceed the available memory...

As for AIX and memory usage, yes AIX tends to manange it's own memory. If the CPU is at 100%, that's another story.

gl

-pd

 

[unixfreak]

Your collegue is right.

Cheers

 

[Yegolev]

specifically make sure your SGA is smaller than real RAM, otherwise you defeat the purpose of the SGA.

AIX will use available RAM (not virtual mem) as filecache, if i remember correctly.

IBM Certified -- AIX 4.3 Obfuscation

 

[sbix]

Hi akam25,
I wrote this script just to see VM activity (which is a good index for mem leakage):
NCAMP=61
if [ $# != 0 ];then
echo $1|grep -Ev "[0-9]" > /dev/null
if [ $? = 1 ];then
if [ `expr $1 \> 200` = 0 ];then NCAMP=$1; fi
NCAMP=`expr $NCAMP + 1`
fi
fi
vmstat hdisk0 60 $NCAMP|awk 'BEGIN { avm=0;fre=0; pi=0;po=0;xfr=0;ncamp=0;frun=0 }
{ if ( $1 ~ /[0-9]/ ) {
if (frun == 1 ) {
ncamp=ncamp+1
avm = avm + $3
fre = fre + $4
pi = pi + $6
po = po + $7
xfr = xfr + $18 }
frun = 1 }
}
END { avm = avm / ncamp
fre = fre / ncamp
npag = pi + po
avgpg = npag /ncamp
xfr = xfr/ncamp
print "VM activity on " 60 * ncamp " sec. "
print "----------------------------"
print "AVG mem pages used "avm
print "AVG free mem pages "fre
print "AVG I/O paging "avgpg
print "AVG I/O on hdisk0 "xfr }'

To capture statistics about VM activity per one hour run:
script_name 60 # (60 = no. of samples)
Results are:
AVG mem pages used in sampling time
AVG free mem pages
AVG I/Os dued to paging
AVG I/Os on hdisk0 (where usually resides paging space)