topic Re: Swapping while memory available in Operating System - HP-UX

Swapping while memory available

Mikael Turvall — Thu, 02 Mar 2006 09:07:39 GMT

I have HPUX 11.23 with 8GB RAM and 20GB of device swap (2 devices)

The server has the system and a couple of additional process on it as a baseline wich takes approx 2GB of memory.

Then I have a batch process that runs a couple of times a day and takes more than 4 GB of memory.

However even though I have allmost 6GB ram free it seems to use a lot of swap. How can that be??

What is reserve memory??

This of course causes a VERY slow processing, and VERY low cpu utilization.

my swapinfo -tam looks like this:

bash-3.00# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4096 0 4096 0% 0 - 1 /dev/vg00/lvol2
dev 16768 1563 15205 9% 0 - 0 /dev/vg00/swap
reserve - 3076 -3076
memory 8180 2067 6113 25%
total 29044 6706 22338 23% - 0 -

Thank you

Re: Swapping while memory available

HGN — Thu, 02 Mar 2006 09:26:18 GMT

Hi

You can check this thread and this might be useful
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=961331

Rgds

HGN

Re: Swapping while memory available

SupraTeam_1 — Thu, 02 Mar 2006 09:54:31 GMT

Hi,
You must use glance if you to exactly see swap.

Re: Swapping while memory available

Mikael Turvall — Thu, 02 Mar 2006 10:05:42 GMT

How can I start glance?
I have tried glance, gpm. What is the path to glance? maybe I don't have it in my path.

Re: Swapping while memory available

Bharat Katkar — Thu, 02 Mar 2006 10:10:43 GMT

Glance is a purchased product but you can use the evaluation copy that comes with the CD kit.
You will have to install it first and then use it for 60 days, later it will be expired.

Regards,

Re: Swapping while memory available

SupraTeam_1 — Thu, 02 Mar 2006 10:10:49 GMT

/opt/perf/bin/gpm

Re: Swapping while memory available

Mikael Turvall — Thu, 02 Mar 2006 10:16:42 GMT

Ok,

I don't have a directory called
/opt/perf

I guess I'll have to ask my hardware guys for the "CD-kit"

Re: Swapping while memory available

A. Clay Stephenson — Thu, 02 Mar 2006 11:49:11 GMT

The "memory" line in swapinfo doesn't mean what you think it does; in fact, in your case, it really shouldn't appear in the swapinfo display at all. You should disable pseudoswap (set swapmem_on=0) because it is useless to enable pseudoswap in a system that has more swap than physical memory. The device swap is being used so you are in fact paging out. You need to run vmstat and examine the pageout (po) column. If that value is > 10-15 (ideally 0) for significant periods of time then you need to add more memory or reduce the memory footprint of your processes.

Re: Swapping while memory available

Mikael Turvall — Fri, 03 Mar 2006 10:53:22 GMT

Can I change lotsfree or desfree ?
In that case. How do you do that?

Re: Swapping while memory available

A. Clay Stephenson — Fri, 03 Mar 2006 11:22:20 GMT

Long before you look at lotsfree and desfree, you need to examine dbc_max_pct and dbc_min_pct. If you are using the default value of 50% for dbc_max_pct then that value is far too large. On a box with 8GB of memory, I would set dbc_max_pct to no more than 15 and dbc_min_pct to about 5 and set swapmem_on=0 at the same time.