Publications by Neil Gunther
May 2011 Guerrilla Classes: Light Bulb Moments
It’s impossible to know what will constitute a light bulb moment for someone else. In the recent Guerrilla classes (GBoot and GCaP), we seemed to be having many more than our usual quota of such moments. So much so, that I decided to keep a list. The first was mine. Asa H. was having trouble setting up PDQ under cygwin on his work-p...
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Go Guerrill-R on Your Data
The Guerrilla Data Analysis Techniques training course (GDAT) will be held during the week of August 8-12 this year. As usual, the focus will be on applying R to your performance and capacity planning data, as well as how to use the PDQ-R modeling tool.(Click on the image for details)Classes are held at our Larkspur Landing location ...
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A Winking Pink Elephant
The title of chapter 5 in my Guerrilla Capacity Planning book is, “Evaluating Scalability Parameters,” and underneath it you’ll see this quote:“With four parameters I can fit an elephant. With five I can make his trunk wiggle.” —John von NeumannIn that vein, Guerrilla alumnus Stephen O’C. pointed me at a recent blog post...
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Q-Q Plots for Multi-modal Performance Data
I’m in the process of putting together some slides on how to apply Quantile-Quantile plots to performance data. Q-Q plots are a handy tool for visually inspecting how well your data matches a known probability distribution (prob dsn). If the match is good, the data should line up more or less diagonally in the Q-Q plot. A common usa...
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GDAT 2011 in Review
As usual, the Guerrilla Data Analysis Techniques (GDAT) class was a total blast. Motivated students always guarantee that. It would really help our scheduling, however, if people didn’t wait until the last nanosecond to register for the class. But given the crazy economic climate, I’m more than happy to do whatever it takes to mak...
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Subjugation to the Sigmas
No doubt you’ve heard about the tyranny of the 9s in reference to computer system availability. You’re probably also familiar with the phrase six sigma, either in the context of manufacturing process quality control or the improvement of business processes. As we discovered in the recent Guerrilla Data Analysis Techniques class, t...
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Visual Illusions: Google vs Facebook vs Yahoo
The ability to visualize data, enabled by the advent of graphical computer tools, has been a great boon to Cap and Perf. The power derives from the way graphical displays provide an efficient impedance match to the visual system in our brain. The weakness derives from the way graphical displays provide an efficient impedance match to ...
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Green Disk Sizing
I finally got around to completing item 5 on my 2011 list concerning electrical power consumed by a magnetic hard disk drive (HDD). The semi-empirical statement is: Power ∝ Nplatters × Ω2.8 × D4.6 . . . (1) where Nplatters is the number of platters on the spindle, Ω is the rotational speed in revolutions per minute...
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How to Generate Exponential Delays
This question arose while addressing Comments on a previous blog post about exponentially distributed delays. One of my ongoing complaints is that many, if not most, popular load-test generation tools do not provide exponential variates as part of a library of time delays or think-time distributions. Not only is this situation bizarre...
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PostgreSQL Scalability Analysis Deconstructed
In 2010, I presented my universal scalability law (USL) at the SURGE conference. I came away with the impression that nobody really understood what I was talking about (quantifying scalability) or, maybe DevOps types thought it was all too hard (math). Since then, however, I’ve come to find out that people like Baron Schwartz did ge...
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