SAR

[khilari]

Hi people, I wanted to ask about sar, lets say it shows a high disk usage, so what do I do next, or if it shows high cpu usage. How do I bring it down?

[Victor Fridyev]

Good question !
You have to find the processes which cause this phenomenon. The simplest way to do this is to install glance and to try to understand how it's possible to find main reasons for overloading and main bottlenecks.

Good Luck

[Bill Hassell]

It's also important to understand what is "supposed" to be happening. After all, if you reduce all disk I/O and CPU usage to zero, nothing gets done at all and your computer just heats up the room.

A really simple shell script can use all of your CPU, and running several du and find commands will create a lot of disk I/O. Is that bad? Not necessarily. There is no reason to worry about CPU and disk usage when you understand how your applications work. As you might expect, 500 users will create a much higher load than 5 users. As with all concerns about performance, you need to know what to expect. You can always reduce the load on the system by kicking users off the system, but that probably not a good solution.

[Dexter Filmore]

You can use the "ps -ef" command to get a listing of running processes. From this you can decide which processes don't need to be running e.g. runaway processes.

[Yogeeraj_1]

hi khilari,

as mentioned above by Bill, high CPU usage may not be necessarily bad! (if it is only temporal)

You should understand your system well and judge if there is any wait event occuring because of one resource waiting on another.

e.g. CPU waiting for I/O

Indepth analysis using Glance and Measureware would help you understand your system better.

hope this helps too!

kind regards
yogeeraj

[Bharat Katkar]

Hi,
Find attached Performance Cookbook.
That will almost highlight every issue and decision making.

Regards,

[Chauhan Amit · Accepted solution]

High Disk Usage - a)Check out the Disk and the logical volume residing on it
b) Logical volume should not be >90% utilised , if this is the case it can cause slowness, add disk.
c) Distribute Logical Volumes across Disks
d) use high speed disks
e) Still Disk usage is high, use Disk Arrays for good performance.


High CPU Usage - a) Find out the application/process consuming most of the CPU - use top, Glance.
b) Tune Application and System Kernel parameters for optimum usage.
c) IF Still the CPU usage(i.e. >90% ) is high after taking all the measures , add cpu to the system.

-Amit

[Geoff Wild]

And here's another link on Performance Tuning for you:

http://docs.hp.com/en/1219/tuningwp.html

And this is a good book:

http://www.amazon.com/gp/product/0131433490/104-0689013-6435940?v=glance&n=283155

Also, if you buy sarcheck, it will give suggestions for you: http://www.sarcheck.com

Rgds...Geoff