swap space is not getting used

[Rajesh T.Panikker]

Hi All,
Kindly Help Me

I have rp 7420 server it's swap space is not using the physical memory is using 98%
then also swap is free.
hp open view agent is also installed this server. hp openview is giving the message of memory bottleneck. the same way i have checked swapmem is 1 is in kernel

re
rajesh

[Steven E. Protter]

Shalom,

I just found this out the hard way. Some software won't allow its process to be swapped. Oracle RAC for example may do this.

Tell us the application involved.

http://www.hpux.ws/?p=6

Just another way to get good performance informaiton.

SEP

[Tim Nelson]

Looks like you need some more device swap.

There is only 8GB of device swap.

The psuedo swap is currenlty at 6GB but that will continually dwindle as memory usage grows and you will not be able to start new proceses.

How much RAM is in this system ?

HPUX allocates swap up front as each process starts. It certainly can be allocated from psuedo swap but as stated this dwindles as RAM is needed and device swap must be there.

Configure devices swap at a minumum of 1x physical RAM. I add 2GB to that for a buffer.

Keep in mind for larger mem systems you will have to modify swchunk as maxswchunks has a limit. ( depending on OS version ).

[Dennis Handly]

This is a duplicate if your following thread and will be deleted. There is no need to create other threads, just add more info (reply) to the existing one:
http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1190829

>hp openview is giving the message of memory bottleneck

This is likely bogus, unless you want to use this as a prediction of adding more applications to this server. (Also what is the size of your buffer cache?)

[Rita C Workman]

To get the full benefit of the memory you have (which we are guessing at) you need to have sufficient swapspace.

Add a disk to vg00. Create another lvol for swap (lvswap). Then go into SAM Under Disks / Swap / Add Device Swap

and add the new disk. Mark it so it is active NOW & On Reboot.

See if that gives you some immediate relief.

Remember that you don't get the full benefit of all your memory unless you allocate the proper amount of swap. Search the Forums for additional information to help you on this and things like maxswapchunks/swchunks (which I always tend just set to 16384/2048) so you can determine what is best for your boxes.

Like I said...just for some quick relief,

Rgrds,
Rita

[Rita C Workman]

..sorry forgot to say...

Since your first (lvol2) is set up for 8Gb, why not just set up the next swap for same size.

/rcw

[Dennis Handly]

>Rita: To get the full benefit of the memory you have you need to have sufficient swapspace.

I'm not sure how helpful this is to have more in Rajesh's case. swapmem_on is on and the 8 Gb of swap isn't being used anyway.
See Bill's replies in these threads:
http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1173007
http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1162266

[Rita C Workman]

Rajesh is showing 98% memory utilization.
The only swap set up is lvol2.
Rajesh is getting out of memory (bottleneck) messages.

Hi Dennis,
The point I was trying to make is that swap should be more than, not equal to physical memory. I'm guessing at what the actual physical memory on the box is.
The recommendation is 2 to 4 times the total physical memory. And I don't see that Rajesh ever added anything other than what the kernel initially built. For all we know afterwards memory was added. We don't know. To handle the increase in processing he should add swap, so that he can advantage of the memory with swapmem turned on.

Rajesh, you can add some swap disk with things up and running and configure your server to use it immediately and on reboots.

Here is a url that will help you on swap that you can review and download as a PDF file for future use.

http://docs.hp.com/en/B2355-90950/ch06s03.html

Rgrds,
Rita

[Dennis Handly]

>Rita: The point I was trying to make is that swap should be more than, not equal to physical memory.

And I was pointing out Bill's opposite view. That you should have "no" swap space and all and everything being left in memory. Of course 8 Gb may not be large enough for Bill's suggestions.

>I'm guessing at what the actual physical memory on the box is.

I assume ~8 Gb from swapinfo "memory".

>To handle the increase in processing he should add swap, so that he can advantage of the memory with swapmem turned on.

You don't need (device/filesystem) swap space to take advantage of swapmem_on.