topic Re: performance problem in Operating System - HP-UX

performance problem

I.Delic — Sat, 17 May 2003 17:41:59 GMT

Hi,
We have a L2000 server.OS is HP-UX 11.11i and we have put 1GB RAM memory in this sever.
We use this sever for our database ( progress).
We have some performance problems. First i saw dat my terminal session works slowly but if i start my session on the console i have the same problem. It is not always but sometimes. I saw that my VHAND proces is very actief. If i start SAR 5 5 then i get wi/0 very big and idle is 0.
We changed a few parameters.

maxuser was 32 and now it is 125
semmns was 128 2048
semmnu was 128 2048

I don't know what can be the problem. I don't have mutch expirance on UNIX but i know what we did change.
When i got this server everything was ok . Then we changed those parameters and now i have a problem. I don't know of this maybe the couse off my problems.
We did install samba server on this machine but if i stop samba server i have the same problem.
I saw that my server does a lot of swap .

can somebody help me

Thank you

Re: performance problem

Michael Steele_2 — Sat, 17 May 2003 18:36:08 GMT

Max semmns is defined by the size of RAM, default = 128, and should be less then or equal to (semmni * semmsl)

Max semmnu is nproc-4, default = 30.

Re: performance problem

Patrick Wallek — Sat, 17 May 2003 18:50:53 GMT

If your vhand process is very active, then chances are you are paging. 1 GB of RAM is not much RAM for a database server.

Post the output of:

# swapinfo -tam

Re: performance problem

I.Delic — Sun, 18 May 2003 10:02:38 GMT

hi,

here is my swapinfo -tam

Re: performance problem

Michael Steele_2 — Sun, 18 May 2003 13:26:59 GMT

Regarding "...I saw that my server does a lot of swap..."
I believe that your swap is just fine based upon this.

Did you change your 'semmns' and 'semmnu' to a value within the ranges indicated?

If problem continues then please attach these reports:

sar -v 5 5
sar -d 5 5
sar -u 5 5
vmstat 5 5

Re: performance problem

Patrick Wallek — Sun, 18 May 2003 15:13:18 GMT

You are using 42% of your swap space. That will slow down your machine drastically.

I would look at adding more memory to the machine. With the price of memory nowadays, I see no real reason why you should EVER use any swap space at all, especially on a machine of this type.

If HP memory is too expensive for your taste, check Kingston ( http://www.kingston.com ). I have used their stuff and it works great.

Re: performance problem

A. Clay Stephenson — Sun, 18 May 2003 17:48:25 GMT

Patrick has nailed it for you. You are never going to be satified with the performance of this box until you increase memory. 1GB is considered very small these days.

One tool to use (if you don't have Glance) is vmstat. The only column of any real value is "po" (pageout). That should be very nearly zero or you will have a dog.

Re: performance problem

I.Delic — Tue, 20 May 2003 17:22:37 GMT

Thank you

Re: performance problem

Ross Zubritski — Tue, 20 May 2003 17:25:35 GMT

Also check dbc_min and dbc_max. Make sure that they are not set to default. I would set min to 2 and max to 5 in your case.

Regards,

RZ

Re: performance problem

Dario_1 — Tue, 20 May 2003 17:30:00 GMT

Hi

I will also recommend Ross answer. Take a look at those parameters and make some corrections to see if that helps.

min 2 or 3
max 5

Regards,

DR

Re: performance problem

I.Delic — Tue, 20 May 2003 17:46:08 GMT

Hi,

Hier is my vmstat file

Re: performance problem

James A. Donovan — Tue, 20 May 2003 18:12:07 GMT

You're system is starving for RAM. You're vmstat (btw, usually a single line of output from this util is not of much use in diagnosis) clearly shows you are running very low on free virtual memory pages. 1429 pages = about 5 MB of free virtual memory. You're actively using 1500 MB of virtal memory. Since you only have 1 GB of physical RAM, you must be swapping. This is a performance killer!

Buy and install at least 1 GB.

Re: performance problem

Michael Steele_2 — Tue, 20 May 2003 20:32:12 GMT

vmstat -s is also nice but this will also do for it indicates that po = 11 and if consistent, then you are paging and you have a capcity problem, which can be corrected by either adding more RAM or reducing the number of processes running on the server.

Re: performance problem

I.Delic — Wed, 21 May 2003 17:16:16 GMT

Hi,
Is it possible with not correct settings of
those parameters:

maxuser was 32 and now it is 125
semmns was 128 2048
semmnu was 128 2048

to slow down performance of my machine.

thank you

Re: performance problem

Jakes Louw — Mon, 22 Sep 2003 05:55:58 GMT

Yes: increasing kernel params means that in many cases you are reserving RAM (memory) for system usage. This reduced the amount of memory that the application or users have access to.

On 1GB, I'd analyse each kernel param, and cut them to the bone.