topic Re: swap Memory in Operating System - HP-UX

swap Memory

Uday_S_Ankolekar — Fri, 22 Jun 2001 14:04:35 GMT

On My N-Class I've 8192 MB memory and swapinfo -m shows the following output
TYPE Avail Used Free
Dev 1024 0 1024
Res - 1024 -1024
Memory 6278 1405 4873 22%

This is Oracle(8x) DB server runs on hp-ux 11.x
Is this configuration ok? or Do I need to change this.

Re: swap Memory

Patrick Wallek — Fri, 22 Jun 2001 14:10:20 GMT

I think I would seriously consider adding somemore swap space to your machine. It appears that you have just 1GB and that it is all used. Your memory looks OK, only 22% used, so you may not be in that bad of shape.

Do you notice any slowness or response time problems?

If it were me, I think I would add more swap space.

Re: swap Memory

Rob Smith — Fri, 22 Jun 2001 14:12:36 GMT

Hi, based on this output I think I would definatley add some device swap. Do so if you have any diskspace free. Hope this helps.

Rob

Re: swap Memory

Bill McNAMARA_1 — Fri, 22 Jun 2001 14:15:13 GMT

Patrick is right,
You are luck enough that swapmem_on = 1 as a kernel default.
You are swapping in memory.

There are lots of links in the forums of responses to kernel tuning and memory management for oracle.

You want to look in the hp-ux -> database forum
where you'll find more.

In the hp-ux -> system administration forum you'll learn how to create swap space (lvcreate -L 1234 -C y -r n ) and swapon on it (/etc/fstab).

Good luck,
Bill

Re: swap Memory

Uday_S_Ankolekar — Fri, 22 Jun 2001 14:18:55 GMT

Thanks for the responces.
There is no complaint as yet from users. But this is further to my earlier query (Compress is slow)http://forums.itrc.hp.com/cm/QuestionAnswer/1,1150,0x9f9e663ce855d511abcd0090277a778c,00.html

How much more swap memory you recommend?

Re: swap Memory

Patrick Wallek — Fri, 22 Jun 2001 14:34:59 GMT

How much available disk space do you have?

I would probably add another 2GB and then monitor swap space usage for a while and then see if you need to add some more.

Re: swap Memory

Uday_S_Ankolekar — Fri, 22 Jun 2001 15:00:51 GMT

I've plenty of disk space available.
thanks for your quick responce.

Re: swap Memory

Uday_S_Ankolekar — Fri, 22 Jun 2001 16:09:12 GMT

Is it possible increase primary swap..?

Re: swap Memory

Patrick Wallek — Fri, 22 Jun 2001 16:25:06 GMT

No, you can't increase primary swap without rebuilding your system from a make_tape_recovery tape (Ignite/UX).

What I would do is just make another LV for swap. You could make it a lower priority than your primary so that it won't get used until the primary gets full. Or you could make it the same priority as the primary so there will be some load balancing.

Re: swap Memory

James R. Ferguson — Fri, 22 Jun 2001 16:36:50 GMT

Hi:

It is very unlikely that you will be able to increase primary swap. Primary swap requires contiguous extent allocation.

You can easily add secondary device swap. Make sure that you assign an equal swap priority as the primary swap, and (ideally) make it the same size to optimize interleaved usage between (or among if you add more than one "secondary") the devices.

You may need to adjust the kernel parameter 'maxswapchunks' in order to allow additional swap declaration. Be sure, too, to enable pseudoswap by setting 'swapmem_on' to one (1).

For a guide to swap managment, take a look at the "HP-UX System Administration Tasks" manual:

http://docs.hp.com/hpux/onlinedocs/B2355-90672/B2355-90672.html

...JRF...