Paging Space Question

[tcorum]

Here is the deal. I have 6 gig of RAM should I have at least 6 gig of swap space? The past 7 days my swap space usage has been slowly moving up until today when it hit 100% and the box stopped taking commands. The box has been up for about 3 weeks running a heavy app with tons of oracle activity. I have currently 6 gig of ram 3 gig of swap space. Any suggestions? I collect data every hour so I can post any stats needed. Also is there some kind of flush command for memory or is a reboot required to get this job done? I have used vmtune to set the max and min perm.

Thanks,

Tcorum

 

[Boria]

Hi Tcorus,
it is right that swap space have to be at least the same as RAM. For app we are using (for example) it must be 2* RAM.
Regards Boris

 

[aixmurderer]

There is a formula to calculate the swap space, unfortunately I don't have it handy right now, but I did find it on an IBM web page.

All I remember is that for our 2GB RAM we had to allow for around 2.25GB swap space.

Our experience was that swap space creep was caused by programs with memory leaks, it was so bad at a stage that we had to reboot once a week to clear the swap space. Our programmers managed to fine-tune them over time to the absolute minimum leaks, we only reboot around every 3 months now. Java programs seems to be our main culprit now. IBM Certified Confused - MQSeries
IBM Certified Flabbergasted - AIX 5 pSeries System Administration

 

[Morsing]

It depends on which version of AIX you're running. In newer versions you shouldn't have 6Gb of swap in any case.

There must be a memory leak somewhere.

Cheers Henrik Morsing
IBM Certified AIX 4.3 Systems Administration

 

[AIXSPadmin]

A question that can't possibly be answered given the limited information. And no professional would attempt to give you an answer that they profess to be correct given the limited amount of data.

 

[tcorum]

AIXSPadmin,

Yes I know it was a limited amount of data but I am willing to post any data needed to get a good answer on this. Thanks to everyone who answered and for your help. I have always heard there was a rule of thumb for swap space and that is what I was trying to get from this post. If there is a rule I haven't found it yet but will continue to look. I wasn't really looking for someone to fix my memory leak but only give there opinion on do they think I have a memory leak. Just wanting someone to confirm what my first guess was. I don't think every post requires a professional answer just some suggestions on where they would look first or maybe a link to some site that gives a little more information then they had before they posted. I look to this forum as a starting point but I always confirm what I am told several times before trying to make changes to production boxes.

Thanks again for everyones help,

Tcorum

 

[tcorum]

To answer your question. I am running AIX 4.3.3 ML 10 on a 6H1 with 6 X 750mhz processors. 6G of RAM 3G swap space. VMTUNE with min max somewhere around 760 for max and 700 for min.. ( I didn't actually go look at the setting so thats a guess. ) I don't use schedule tune for memory settings. The box runs Oracle 8.1.6.3 with Peoplesoft / Peopletools 7.5, 7.6 We run microfocus cobol suite that drives a ton of COBOL code for a special Peoplesoft CIS app. I have about 130 users of the product that hit it all day then we run batch all night. I collect svmon, sar, vmstat, iostat, ps details, and run nmon every hour on the hour so if anyone has a question about what the stats look like please just let me know.

Thanks,

Tcorum