topic Re: Max'd memory in Operating System - HP-UX

Max'd memory

Otto Folprecht — Tue, 20 Jul 2004 11:43:25 GMT

Hi All, I have a HP7410 with 2GB RAM. When looking at Glance I see that I am currently utilizing 99% of memory and swapping is 50%. So do I just reboot the system and flush the memory or should I check the memory why is it max'd out and what should I do to take control. BTW using UX11. THX Otto

Re: Max'd memory

RAC_1 — Tue, 20 Jul 2004 11:49:29 GMT

I doubt that your buffer cache settings are at default.

Check them

kmtune -lq dbc_max_pct
kmtune -lq dbc_min_pct.

The default value is at 50 % and then you will watse a lot of memory for that. Buffer cache(dynamic) is ok at 5-10%

Also UNIX95= ps -ef -o "vsz,args,ruser"|sort - rnk1 will give you the list of who is using the maximum memory

Anil

Re: Max'd memory

Steven E. Protter — Tue, 20 Jul 2004 12:13:21 GMT

These two numbers

kmtune -lq dbc_max_pct
kmtune -lq dbc_min_pct.

should not be set to far apart. Mine are 5 for min and 7 or 8 for max.

It's very expensive to change that settigns in terms of cpu and performance.

More on perf tuning.

http://www2.itrc.hp.com/service/cki/search.do?category=c0&docType=Security&docType=Patch&docType=EngineerNotes&docType=BugReports&docType=Hardware&docType=ReferenceMaterials&docType=ThirdParty&searchString=UPERFKBAN00000726&search.y=8&search.x=28&mode=id&admit=-1335382922+1090343493238+28353475&searchCrit=allwords

I'm attaching a good perf data collection and script and some advice.

Just because a system usues its memory is not necessarily a problem. Its in there, there is no problem with using it. The thing you want to look for is specific performance problems.

SEP

Re: Max'd memory

Rita C Workman — Tue, 20 Jul 2004 12:16:04 GMT

Please run swapinfo -tam and post....

Rita

Re: Max'd memory

Otto Folprecht — Tue, 20 Jul 2004 12:56:12 GMT

Here is the info Rita. THX Otto

Re: Max'd memory

Otto Folprecht — Tue, 20 Jul 2004 12:58:36 GMT

One more time, I hope it works. The attacment is the swapinfo -tam. THX Otto

Re: Max'd memory

Patrick Wallek — Tue, 20 Jul 2004 13:11:54 GMT

You are definitely paging out.

What kind of application are you running on this machine? 2 GB of RAM on an rp7410 is not much at all. The first thing I would do is bump that amount up. I'd do a least 6 and maybe 8GB.

At a minimum you need an addition 1100 MB or so since that is what is currently sent to your device swap.

Re: Max'd memory

Rita C Workman — Tue, 20 Jul 2004 13:40:33 GMT

Hi Otto,

Patrick has definitely summed it up...you are paging out. And depending on what your running, and how well it runs and releases resources, you definitely need to increase your memory.
On the application side..you might watch this. If you set your maxdsize (max data segment size ) and your maxssize (max stack segment size) too high, than an application can take up more resources. If it is coded poorly or doesn't releases resources well...you will feel it with high mem utilization. I try to hold these values as low as I possibly can, cause I have run into too many 'cowboys' who haven't got a clue what their lousy app is doing to the system (and care even less)...

So there are a number of things to watch for. GlancePlus is good for watching some processes to see who might be hogging more than they should. And with only 2Gb, you need to guard it closely.

But take Patrick's advice.....request another 6Gb of memory.

Just a couple thoughts,
Rita

Re: Max'd memory

Bill Hassell — Tue, 20 Jul 2004 13:46:50 GMT

There is no reason to reboot. 100% RAM usage and 50% swap usage is fine. You have room for some more programs to run before you hit 100%. Oh, are you having serious performance issues? Then you need a minimum of 4Gb of RAM, 8Gb to be sure. Swap usage (not reserved, actually used as seen by swapinfo -tam) generally indicates you don't have enough RAM. Rebooting merely starts everything over again and you'll get to the same place.

Memory usage by itself is not bad, page out is...because the processes will not all fit in RAM. There are many question to answer: what are you running? How much RAM is used for processes and how much for shared memory? If this is a database server, your DBA may be optimizing database memory for performance but does not realize that the system needs more RAM.