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The Art and Science of AIX Performance: Firmware, History and More

AIX Performance

Over the past two years, I’ve shown you some advanced techniques for analyzing AIX system performance and fixing the performance issues you uncover. The response to these articles has been heartening; it seems many of you have put these techniques into practice, with beneficial results.

However, the reader emails I receive typically consist of two parts. The first part details the successful implementation of suggestions from my articles―and again, this is nice to hear. As for the second part, it generally takes the form of a question, like: “How can I develop a methodology to attack my performance problems from the time I discover them, through analysis and remediation?”

Without a doubt, performance tuning is the greatest art in computer management. But the sad truth is that there's virtually no documentation that explains how to get peak performance out of your existing systems, from within your current hardware and software configurations. This article, the first in a series, is my attempt to rectify this.

We will, of course, confine ourselves to AIX system performance, but the principles I’ll delve into can be applied to most any computer, because all computers are constructed the same way: they have a certain number of CPUs, along with some quantity of memory, and they're supported by networking and storage devices. Even the new field of quantum computing follows this basic architectural model. The main differences come in the software that computers run―the operating system foremost, but also databases, applications, middleware and utilities.

These commonalities even apply to computer documentation. I studied a handful of system performance manuals for several different operating systems, not just AIX, and found that these docs do a reasonably good job of covering the basic commands used in performance analysis. Unfortunately, there's next to nothing about intermediate techniques of performance analysis and remediation. Even more striking, there's utterly nothing about advanced techniques. In short, what's needed is a soup-to-nuts, holistic methodology of dealing with the performance issues we all encounter. And this is what I'll attempt to provide.

In this series I'll detail my method of attacking and fixing performance problems. I’ll share how I think about performance and provide a roadmap to get you from diagnosis through remediation. I'll explain how I use many of the performance tools that are supplied for AIX―and then tell you how to use them in different ways. Ultimately, I'll encourage you to develop your own perspective on these matters, using your unique roadmap to navigate your own environment.

One final thing before we dive in: Please give some thought to the title of this article, “The Art and Science of Performance.” For sure, the scientific method is prominent when it comes to observing and evaluating systems with less than desirable performance. You'll take logical steps that lead to your goal. You'll formulate a hypothesis as to what’s wrong and how to go about fixing it. You'll then test your hypothesis by various means, altering your thinking on the subject as required until you resolve the problem.

Further, you'll encounter inviolate rules when analyzing your problem, like a CPU’s timeslice or dispatch wheel. You’ll deal with finite resources like memory and learn the limits of performance tuning. You'll follow, as you should, many rules of IBM Power Systems hardware.

But when it comes to attacking performance problems that impact your hardware and everything it runs, it's essential that you understand this: in performance analysis and tuning there are no rules. Performance is science, but it's also an art. Everything is open to interpretation. All that matters is what works in your particular situation.

The Importance of Firmware

So, where to begin? How about if I get into the philosophy and method of performance analysis and remediation for the four main subsystems I just mentioned: CPU, memory, networking and storage.

I will tell you all about this―but not just yet. First, I need to point out another thing that's missing from those performance manuals I looked through. It's a gap I'm at a loss to explain. It's firmware. Whatever you call it―the BIOS, microcode or firmware―the labels all represent one thing: embedded software that allows you to maximize performance and stability with all your systems, be they Power Systems servers, mainframes or PCs. Firmware is important because it's the area of systems management that can actually prevent many problems before they become performance issues.

Updating and maintaining current firmware levels in your AIX systems should be a routine part of every administrator's job. But many things can thwart that routine, the biggest of which is downtime. Many of your sites are running applications that require 24 X 7 availability. Taking a system down for firmware maintenance is something management may not tolerate. The alternatives that allow you to conduct firmware maintenance without incurring downtime may not be available to you, either. You may not have Live Partition Mobility (LPM) setup to move your production LPARs from one frame to another while your application is live. You may not have a high availability mechanism in place to fail an LPAR to another frame so that downtime is minimized.

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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