AIX > Administrator > Performance

Diagnosing and Tuning with PerfPMR: Setup and Execution

IBM performance issue
 

Everyone uses PerfPMR, a suite of performance and configuration diagnostic programs. But do you really how to use PerfPMR? While there are dozens of different ways to run all, or parts of, PerfPMR, there's little documentation that explains how to do all the things you can do. In this four-part series of articles, you'll learn how to get the most from this comprehensive tool.

If you've ever opened a PMR with IBM for a performance issue, it’s likely you have been asked to run PerfPMR for diagnosis. Once you upload the data to IBM, performance experts analyze it and make remediation suggestions based on the data it presents.

This passive method of PerfPMR usage works well for many busy administrators. However, plenty of admins would like to explore different methods of running PerfPMR and learn about the data it produces.

Download and Setup

So you’ve discovered a performance problem on one of your AIX systems. Maybe a database is running slowly, or an application has ceased communicating with users. Or perhaps you’ve noticed your CPU usage has climbed precipitously overnight for no obvious reason, or network traffic has slowed to a crawl. You try a few familiar tricks, but they don't eliminate the problem. What now? Try the PerfPMR utility.

But before actually downloading PerfPMR and running it on your suspect system(s), some prep work is in order. For starters, placement matters. You can’t – or shouldn’t – install the PerfPMR executables just anywhere. I always tell customers to stay away from / (the root filesystem) and /var, for the obvious problems that may emerge if these filesystems are filled to capacity with PerfPMR data. Also, do not install and run PerfPMR into an NFS-mounted filesystem. Doing so results in confused data from both the NFS server and client, and you certainly don’t want that. I recommend installing PerfPMR either into /tmp or /home; these locations typically contain enough space to run PerfPMR, plus they're easy to remember.

Let’s say you’ve settled on /tmp for your PerfPMR installation. In the /tmp directory, create two subdirectories called “PerfPMR” and “perfdata,” respectively. cd into the /tmp/PerfPMR directory. Then, using either a web browser or FTP from the command line, download the PerfPMR archive along with the README into the /tmp/PerfPMR directory. For convenience, here's the FTP link from within a browser:

ftp://service.boulder.ibm.com/aix/tools/perftools/perfpmr/

Once you arrive at this URL, you'll find many folders. Each holds a PerfPMR version that's tailored for a specific AIX release -- from the current v7.2 and all the way back to v3.2. Go into the folder that corresponds to the AIX version your problem system is running and download both the README and tar archive of PerfPMR.

Next, follow the unpacking and installation instructions in the README; they’ll take all of a minute to execute. When you complete the installation, you’ll have about 50 distinct executables in your /tmp/PerfPMR directory (including shell and awk scripts with a few C routines tossed in). A link will also have been created to /usr/bin, pointing back to the perfpmr.sh file in your /tmp/PerfPMR directory. This is the “master control” file, so to speak, for a typical PerfPMR run. Scan the contents of this directory and familiarize yourself with the files it contains. We’ll cover some of these in future articles.

The first thing you need to check is whether you have the space to store all of the reports PerfPMR will generate; at minimum, there will be a few dozen. PerfPMR cannot be run from its installation directory, so cd into your /tmp/perfdata directory and issue this command: 

perfpmr.sh -P 

This produces a screen full of information. In the last two lines of this text, you’ll see something like this:

PERFPMR: disk space needed is at least :  <490> Mbytes
PERFPMR: free space in this directory  :  <4112> Mbytes

If you have enough free space to accommodate the PerfPMR data, you’re good to go. This step is very important because the last thing you want is to have your PerfPMR run aborted because you don't have enough space for the data.

Execution

Now that you’ve installed PerfPMR and verified you have the space needed for all of its reports, you're ready to run the utility. Running it in default (the preferred option, at least initially) is easily accomplished – as the root user – with this command:

perfpmr.sh 600 <enter>  

 

Mark J. Ray has been working with AIX for 23 years, 18 of which have been spent in performance. His mission is to make the diagnosis and remediation of the most difficult and complex performance issues easy to understand and implement. Mark can be reached at mjray@optonline.net



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