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Problem?

Problem?

A 11.0 N-class w/ 16 gig RAM has a memory util between 70-90%, 4 gig swap space, 78% pseudo-swap used, and a mem pageout rate between 1 and 3 p/s. Does any of this indicate future problems if the machine continues to grow a bit?

Thanks
6 REPLIES
JAYAMOHAN.V.D
Occasional Advisor

Re: Problem?

hi,
As per me, 90% memory usage is a bit high, still if the swap usage is less, and if ur applications doesnt show much performacnce problems, u dont require an immediate upgrade.

but if u r planning to add more users / applications , i think u may have to upgrade the memory.
i know the installations with 80 to 90 % memory usage in the paek time and 20 to 30 % of device swap usage running with out much performance problems.
u have to check out how much device swap is getting utilised.
regards
jayamohan

A. Clay Stephenson
Acclaimed Contributor

Re: Problem?

Hi Dan,

Things don't look too bad but I don't like to see any pageouts. You bought all that memory so that you wouldn't have to swap at all. If this is peak, I wouldn't worry about it but if not you could use more memory. There may be a very simple solution. Is dbc_max_pct at the default 50%, if so lower it to about 10% or less.

Clay
If it ain't broke, I can fix that.

Re: Problem?

Jayamohan,
My device swap is not allocated at all, but completely reserved from what I can tell. That's why it is going to the psuedo swap.
Jim Turner
Esteemed Contributor

Re: Problem?

Dan,

Regarding Dynamic Buffer Cache, it has been my experience that more than about 300MB's worth is a waste. The hit rate doesn't get much better (and in fact usually gets worse) with larger dbc's, although your mileage may vary. With your memory model, I'd set both dbc_min_pct and dbc_max_pct at 2. That should delay any potential memory pressure you might experience by adding users/apps.

Fire up Glance and do an "m" for the memory report. Watch the VM Reads and Writes. If you are getting *consistent* VM Reads and Writes, you need to pour on some more RAM. If not, high memory utilization simple means you're getting your money's worth out of your hardware. And that's a good thing, right? How much dosh are you willing to shell out to see a metric drop to a more "comfortable" level? ;-)

Cheers,
Jim

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Re: Problem?

Clay,

My dbc upper is @ 10%. If I add swap space it will relieve some of my psuedo-swap and therefore memory, correct?
A. Clay Stephenson
Acclaimed Contributor

Re: Problem?

Hi Dan,

Not exactly, more swap space will give you more headroom in case you need more process space. That is, you can run processes before system resources are exhausted. The only thing that will relieve swapping is more memory (or freed memory).

10% dbc_max_percent is still fairly high in mosy system with 16GB. Exceptions might include a large NFS server. If this box is primarily a database server, I would set bufpages to a non-zero value (81920 - 320MB and that is very generous) to disable dynamic buffer cache. Next, in this case if it is a database server, I would consider reducing the size of the SGA. Almost anything is better than seeing pageouts.

Clay
If it ain't broke, I can fix that.