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Re: How much paging is excessive

 
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How much paging is excessive

Hi everyone -

We've got an N class server with 10GB of memory and 14GB of swap space configured.

Memory utilization from glance peaks at 100% but over a 2 day period only 92MB have been paged out. Is that amount of paging out enough to warrant adding more physical memory? Will a performance increase be noticed?

Thanks!
5 REPLIES 5
James R. Ferguson
Acclaimed Contributor

Re: How much paging is excessive

Hi:

If paging is low, but memory is simply inuse, I wouldn't worry. If you have your buffer cache ceiling ('dbc_max_pct') still at the default value of 50% then you should lower it. That may be your culprit.

...JRF...

Re: How much paging is excessive

dbc_max_pct is set to 5 and dbc_min_pct is set to 3.
Stefan Farrelly
Honored Contributor
Solution

Re: How much paging is excessive

Your dbc max and min are fine (3-5% of 10GB being 300-500 MB. Recommended max is upto 500 MB so thats fine).

If youve only got 90MB paged out then thats not too bad. It will be affecting performance very slightly though. Optimally you would want to have nothing paged out at all. Check using the vmstat command during peak hours of the day to see the pageout/pagein rate (vmstat 1 10) and if the pi/po columns run > 3 or more then I would try to reduce memory usage, or if you cant and have the cash to burn, increase ram - for optimal performance.
Im from Palmerston North, New Zealand, but somehow ended up in London...
Praveen Bezawada
Respected Contributor

Re: How much paging is excessive

Hi
Generally a value 10 for dbc_max_pct is considered appropriate but the exact value is application dependent.
And what is the number of page faults generated over the same interval.

Br
Praveen

Re: How much paging is excessive

There were about 16 million page faults during the 2 day period. Wow.