Hi,

Memory utilization of AIX5.3 always remain high, more than 98% even if there will be no load.

System Model: IBM,9131-52A
Machine Serial Number: 06C021G
Processor Type: PowerPC_POWER5
Processor Implementation Mode: POWER 5
Processor Version: PV_5_3
Number Of Processors: 2
Processor Clock Speed: 2097 MHz
CPU Type: 64-bit
Kernel Type: 64-bit
LPAR Info: 1 Srvconfigdb
Memory Size: 7952 MB
Good Memory Size: 7952 MB
Platform Firmware level: SF240_403
Firmware Version: IBM,SF240_403
Console Login: enable
Auto Restart: true
Full Core: false

Paging Space Information
Total Paging Space: 8192MB
Percent Used: 4%


Kindly suggest.

Regards,
Shankar

AIX uses memory like that.
Any spare memory is used for file page cache.
As long as pi, po in vmstat remains low then this is normal for a properly tuned system.

If you download the nmon tool you can get a better grasp of how much of your RAM is being utilised for filesystem cache. Press 'm' for memory when you load it. I think topas also gives some indication with the comp noncomp values. The %noncomp value is whats being used for filesystem cache. Like Duke said, AIX will try use all its memory as best it can to boost performance. If the machine requires the memory then memory used for filesystem cache will start to get released back for process usage.

What application(s) are you running on the system and do they have maxperm memory values? Have you noticed any "zombie" processes running, or large amounts of respawns of running processes? Do you have anything running incessantly in the background such as monitoring of other systems, some agents or polling of some type? While AIX does enjoy using memory, I wouldn't call it "normal" for a system to just sit around using 98% of it's memory. Is this system virtualized or running standalone? If it's virtualized, is it part of a shared memory pool?