topic Re: mem usage on hp systems in Operating System - HP-UX

mem usage on hp systems

Karl oliver — Wed, 12 Oct 2005 20:34:30 GMT

I often have the debate on mem uage on hp systems. I wish to know avail and used mem on system. People tell me this is not important that amount of paging is- true of course. But I maintain that if you only have 10meg of mem avail on sys then you are going to be paging.
For our informix dbs we make the shared mem resident so it wont page so amount of mem avail on sys is critical when setting up dbs to run efficently.
Also if you are not monitoring amount of mem available on sys how do you know if you have installed an inefficent software release. We just did this . Our mem usage increase by 1 gig overnight- how do I know - by monitoring mem usage !
Any comments from the experts out there

Re: mem usage on hp systems

Arunvijai_4 — Wed, 12 Oct 2005 22:54:10 GMT

You can use #top -s1 to find out memory usage.
or,
UNIX95= ps -e -o vsz,uid,ruser,args | sort -rn

-Arun

Re: mem usage on hp systems

Lee Harris_5 — Thu, 13 Oct 2005 04:50:59 GMT

If you have glance installed: glance -m

HTH

Re: mem usage on hp systems

Muthukumar_5 — Thu, 13 Oct 2005 05:07:20 GMT

Check the swap size and memory. You've to configure swap memory related with physical memory.

# swapinfo -tam

You can put a script like,

#!/bin/ksh
# memusage.ksh
while [ 1 ]
do
date >> /tmp/memory.log
UNIX95= ps -ef -o sz= -o vsz= -o pid -o comm | sort -nkr >> /tmp/memory.log
# five minutes sleep
sleep 300
done

# end

# chmod u+x memusage.ksh
# ./memusage.ksh 2>/tmp/memory.err &

Check with /tmp/memory.log and /tmp/memory.err for information and error(s) if any.

hth.

Re: mem usage on hp systems

VEL_1 — Thu, 13 Oct 2005 06:28:47 GMT

Hi,

Just look at the following link which has Script & C program also:

http://forums1.itrc.hp.com/service/forums/parseCurl.do?CURL=%2Fcm%2FQuestionAnswer%2F1%2C%2C0x026250011d20d6118ff40090279cd0f9%2C00.html&admit=-682735245+1129202554424+28353475

Thanks.

Re: mem usage on hp systems

Borislav Perkov — Thu, 13 Oct 2005 07:35:41 GMT

Hi Karl,

here are two scripts one is for top memory use and other is for claimed memory used.

Regards,
Borislav

Re: mem usage on hp systems

Borislav Perkov — Thu, 13 Oct 2005 07:36:22 GMT

here is memtop.sh

Re: mem usage on hp systems

Kent Ostby — Thu, 13 Oct 2005 09:45:47 GMT

Karl -- When it comes to memory usage and swapping, I find that the two most common errors are:

1) Leaving dbc_max_pct, nbuf, and bufpages at 0 on large memory systems. That leaves (be default) the dbc_max_pct set to 50 so you have 1 gig of a 2 gig system going to dbc. I suggest a dbc_max_pct that uses at most 750 to 800 MB.

2) Not having enough device swap space. HP still recommends in general that you have 2xRAM worth of device swap (i.e. 4 GB of device swap for 2 GB of RAM).

Monitoring it is essential of course regardless of which of these tools you use.

Re: mem usage on hp systems

Karl oliver — Thu, 13 Oct 2005 14:20:03 GMT

Kent
is this still true
HP still recommends in general that you have 2xRAM worth of device swap (i.e. 4 GB of device swap for 2 GB of RAM).

We have 16 gig mem but dont have 32 gig swap
.
below shows mem as being used for swap so at what stage do you worry about swap space below show no swap disk space. - agrees with sam - but not swapinfo !
have found prog memdetail that shows following
Memory Stat total used avail %used
physical 16382.0 9294.9 7087.1 57%
active virtual 9280.9 4342.1 4938.8 47%
active real 8826.0 3948.3 4877.6 45%
memory swap 13240.2 5313.8 7926.4 40%
device swap 8192.0 8189.3 2.7 100%

Re: mem usage on hp systems

Geoff Wild — Fri, 14 Oct 2005 09:43:18 GMT

Your device swap is full - you should increase it - to atleast the same size as your ram...

This does not mean you are "swapping" in the traditional sense - it is just a place holder for what is already in memory...

Rgds...Geoff

Re: mem usage on hp systems

Karl oliver — Mon, 17 Oct 2005 20:51:12 GMT

Geoff I dont think system is out of swap space or everyhing would have died !
As i showed above mem info line below shows memory is being used for swap is the correct ?
Memory Stat total used avail %usedmemory swap 13240.2 5313.8 7926.4 40%

this is governed by kernal param swapmem_on
Some say have it on others say have it off !
what do the experts say ?

the HP-UX Performance Cookbook paper by Stephen Ciullo and Doug GrumannRev.
recommends having pseudo swap off

Re: mem usage on hp systems

Karl oliver — Sun, 06 Nov 2005 19:32:36 GMT

Does not seem to be anyone out there that really knows hp mem usage in detail. No one mentioned the
kernal param swapmem_on -pseudo-swap and how it works. with this set uou can have disk swap all used and still work