topic Re: System memory usgae in Operating System - HP-UX

System memory usgae

Steve Lee_7 — Mon, 14 Aug 2006 09:33:23 GMT

Hi

I have an rp4440 server with 1 GHz * 4 CPU and 10GB memory
I noticed that system memory usage is about 4GB/10GB total memory on glance
Customer asked me to reduce system memory size
Is there anyway to resize system memory size?
I need to explain what root cause is

Re: System memory usgae

A. Clay Stephenson — Mon, 14 Aug 2006 09:40:31 GMT

You want root cause and supply essentially zero data? The most probable cause is the default dbc_mac_pct value of 50% which controls the size of the dynamic buffer cache. You should reduce dbc_max_pct to no more than 15% and dbc_min_pct to about 5%. You may also have other tunables that are badly set but the most likely are the buffer cache tunables.

Re: System memory usgae

inventsekar_1 — Mon, 14 Aug 2006 09:58:12 GMT

Lee, As clay told, it is always better to give *more than enough* information.

reply datas like, what applications u r running, is it a production system or going to be production soon, also, check the memory usage with other tools also...[** glance may be wrong sometimes(i think)**]

Re: System memory usgae

Steve Lee_7 — Mon, 14 Aug 2006 10:08:47 GMT

I have checked the buffer cache size
It is less than 1GB

Here is memory status on glance and screen shot

Total VM : 7.62gb Sys Mem : 3.83gb User Mem: 5.20gb Phys Mem: 10.0gb
Active VM: 7.56gb Buf Cache: 819.0mb Free Mem: 172.5m

Re: System memory usgae

Michael Steele_2 — Mon, 14 Aug 2006 11:06:41 GMT

The problems not with your system memory utilization its with your application memory utilization. Can you provide what's running atop the O/S? SAP, Oracle?

I've attached a script for you to look at and run. Can you paste in the values of the kernel parms. listed in this script?

Re: System memory usgae

rayche — Mon, 14 Aug 2006 21:20:22 GMT

Pls try to reduce vx_ninode parameter, in fact , HPUX use VXFS, and VXFS use its own parameter "vxfs_ninode" to keep a large cache in system memory , you can reduce it and the system memory will release, pls do it as following :
1. Find the default number of vxfs_ninode
echo "vxfs_ninode"|adb /stand/vmunix /dev/mem

2. Adjust the parameter to 20000 if your machine is not file server

SAM--->vx_ninode=20000

Thanks.

RayChe

Re: System memory usgae

rayche — Mon, 14 Aug 2006 21:36:37 GMT

Sorry , to the first step,the correct is :

echo "vxfs_ninode/D"|adb /stand/vmunix /dev/mem