Edit: Some links no longer work.
Originally posted December 13, 2011 on AIXchange
Nigel Griffiths had a great session at this fall’s IBM Technical University on “nmon, topas and Friends.” I assume that you know that he actually wrote nmon (aka, “Nigel’s Monitor”). As such, it’s very enlightening to hear him speak about the history of the tool and his motivation for writing it. Besides, obviously, being very knowledgeable about the subject, he’s also a very entertaining and engaging public speaker.
Nigel mentioned how nmon and topas had come together, and detailed the history and timeline around nmon being officially supported by IBM. He then offered some tips and tricks for running both tools.
He mentioned that current versions of AIX (which you should be running) include a copy of topas_nmon. I assume it’s on your machine if you’re reading this post. We should all be using the current version. nmon “classic” should only be used if you’re running old versions of hardware and AIX, although Nigel recommends using ONLY the latest version (12e+). Keep in mind that nmon classic is functionally frozen.
Nigel said this endeavor started as a personal project, but he was soon deluged with requests for copies. He explained that the tool consumes less than 1 percent CPU and uses APIs, rather than AIX commands, under the covers. This is how he accomplished his goal of making nmon “small, simple and safe.”
While I can’t capture everything Nigel laid out in his presentation, I do encourage you to experiment and learn more about the tool. Run nmon –h and look at all of the different available options and statistics. As IBM now supports both nmon and topas, you have a choice when it comes to viewing performance data and talking to IBM about what you’re seeing on your systems.
With topas, see what you get by entering “P,” “E,” “D,” “L,” “V” or “F.” Be sure to capitalize. “E,” for instance, is for shared Ethernet adapters. Log into your VIO server, run topas and hit “E,” and you’ll see the network traffic going across your shared Ethernet adapter.
If you’re running virtual SCSI devices, try “D”–and then “d”–inside your VIOS to view virtual to physical disk mapping information.
Topas –C gives you a view of all the LPARs across your physical machine (assuming you can access each LPAR over the network).
One nice thing is if you’re on a system and topas keeps refreshing, you can freeze the screen to conduct closer analysis. Just hit the space bar.
Now try nmon. Hit “l” (that’s a lower-case L) and watch as it gives you a long-term view of physical CPU. If you observe the display over time as your CPU works and idles, you should see the scale automatically change based on your machine’s activities.
Nigel also mentioned how we can use the Stephen Atkins tool, nmon analyzer, to graph and view our nmon output.
What are some of your favorite ways to customize your topas or nmon views?
As I’ve often noted, the IBM Technical University is a great educational experience. I think every one of Nigel’s sessions was standing-room only, and I know that Jay Kruemcke had to add another session on AIX trends and directions. I’m sure other presenters drew large crowds as well. The 2012 conference will be held in Las Vegas. Plan now so you can attend.