topic Re: Total amount of system memory in Operating System - HP-UX

Total amount of system memory

panks — Sat, 17 Jan 2009 00:53:33 GMT

Hi,

My system is having 64GB of total memory and when I checked with glance -m I found that system is consuming more than 10GB of memory.
Can you please suggest how this can be reduced or is this the standard:

Total VM : 30.3gb Sys Mem : 10.4gb User Mem: 33.5gb Phys Mem: 63.7gb
Active VM: 26.1gb Buf Cache: 6.4gb Free Mem: 13.5gb

Re: Total amount of system memory

sujit kumar singh — Sat, 17 Jan 2009 06:54:29 GMT

it is showing that 10 GB of the entire memory that ur system has is being used as a SYSTEM Memory that is the memory that has been reserved for the System Processes for HP-UX ...

do a

#dmseg| grep -i physical

what does that show, that is teh actual memory Physically installed in ur server.

alao u can see memory amount installed as in

do the cstm commsnd

#cstm
cstm>sel all
cstm>info;wait
cstm>infolog

and u can see the Memory Specications at the end of this display.

do not fprget to assign points please.

Regards
Sujit

Re: Total amount of system memory

Javed Khan_1 — Sat, 17 Jan 2009 12:42:07 GMT

Hi,

Check dbc_min_pct and dbc_max_pct if set to 5 and 50 (default)

set it to dbc_min_pct=3 & dbc_max_pct=5

Javed

Re: Total amount of system memory

panks — Sun, 18 Jan 2009 17:32:39 GMT

Thanks but when I checked dbc_max_pct and dbc_min_pct its value is 10 and 5 resp.

And the usage of dbc_max_pct is 100% so reducing the value of it may cause problem.

Please suggest. I want to know that out 0f 64 GB that reserved ~11GB for system is that standard value. I mean 25% of total memory, or it can be changed.

Re: Total amount of system memory

Steven E. Protter — Sun, 18 Jan 2009 17:43:19 GMT

Shalom,

swapinfo -tam is fairly easier to understand.

It also shows swap.

This figure: Phys Mem: 63.7gb
Shows the system is recognizing all physical memory.

The way I see your display, is system memory, which includes SGA and scuh use is 33.5 gb, the system memory, for OS and such is using a surprisingly high 10.4 GB, but that figure depends on what services you have running.

SEP

Re: Total amount of system memory

bibith dathan — Mon, 19 Jan 2009 06:28:58 GMT

Hi

Please post more details of application which running on server .

Bibith

Re: Total amount of system memory

Jeeshan — Mon, 19 Jan 2009 07:54:59 GMT

no actually you need to calculate the dbc parameters according to your physical memory.

your parameter is already set to *_max = 10 then try to monitor which system processes are consuming more memory.

check with this command

#export UNIX95=1;ps -ef -o comm,pcpu,vsz,args |more

Re: Total amount of system memory

Dennis Handly — Mon, 19 Jan 2009 12:15:27 GMT

>ahsan: export UNIX95=1;ps -ef -o comm,pcpu,vsz,args

You don't want to export UNIX95, you just want it temporary:
UNIX95=EXTEMDED_PS ps -ef -o comm,pcpu,vsz,args

Re: Total amount of system memory

panks — Mon, 19 Jan 2009 15:45:27 GMT

Thanks for your reply but the system memory is constant since we configured the system that is 10.4 GB. One more thing as dbc_max_pct was set to 10 it was 100% utilized so I have changed the value of dbc_max_pct to 25. Please suggest how we can reduce the value of system memory or is it the standard value I mean 25% of total memory.

Re: Total amount of system memory

TTr — Mon, 19 Jan 2009 16:31:57 GMT

So a lot of your memory is used up for kernel buffer cache. Normally you don't need taht much buffer cache. For a server like yours I would chose min 1% and max 2% or at most 2%min and 4% max. The buffer cache will always be at 100% if the server is busy.

Now for the system memory, 10.4GB out of the 64GM mmeory is about 15%. That 's probably normal for a busy server and the newer itanium servers. It all depends what the kernel is doing, a lot of new i/o, paging etc. Need to look further in the process activity as already mentioned.

Re: Total amount of system memory

Steven E. Protter — Mon, 19 Jan 2009 16:35:13 GMT

Shalom again:

One more thing as dbc_max_pct was set to 10 it was 100% utilized so I have changed the value of dbc_max_pct to 25. Please

That uses a lot of space for the buffer pool.

I normally use 5 and 7 (max) on an Oracle based system. For 11.11 and below buffer pool increase does not help with Oracle performance anyway.

Changing the buffer pool is extremely expensive for a system in terms of performance. Having those numbers so far apart is bad for overall systems performance.

SEP

Re: Total amount of system memory

panks — Mon, 19 Jan 2009 17:21:40 GMT

Thanks Steve!! So you mean I should revert back the value of dbc_mac_pct to 10%. One more question is this parameter only responsible for oracle. And is going to create any problem if utilization of dbc_max_pct is continously at 100% because user has already faced a problem one time and their entire oracle instance hung.

Re: Total amount of system memory

panks — Mon, 19 Jan 2009 17:31:04 GMT

Ok I have reduced the value of dbc_max_pct now but still the buf cache is at same value.

Re: Total amount of system memory

Dennis Handly — Tue, 20 Jan 2009 00:15:30 GMT

>I have reduced the value of dbc_max_pct now but still the buf cache is at same value.

Which? Size or percent? For the former, it may take some time to reduce it.

Re: Total amount of system memory

Javed Khan_1 — Tue, 20 Jan 2009 02:47:20 GMT

Also check with dba if kernel tuning is correct with respect to the oracle version running on your system , or may be they need to so some performance tuning at db end

Re: Total amount of system memory

panks — Tue, 20 Jan 2009 18:57:31 GMT

What does that mean, do you mean to say if there is not proper tuning at DBA end then system memory will consume more.
Is there any way by which I can cut down the usage of this big amount of system memory and free up it for the use of user processes.

Thanks

Re: Total amount of system memory

Javed Khan_1 — Sun, 25 Jan 2009 08:27:52 GMT

please paste the output of glance/top showing process based memory utilization