The Bob's Honest Truth Bob Sneed's Blog

Of the many articles and postings I find on the subject of 'direct I/O', most are flawed by statements which are too broadly phrased to be fully 'true'. Therefore, I've challenged myself in this blog entry to digest the topic into a space smaller than a whitepaper, but bigger than an E-Mail. My mission here is to disambiguate the terminology and promote a common vocabulary for discussion of related topics. It is a pretty geeky topic though, so the language here assumes a certain degree of geekiness and interest in the topic on behalf of the reader. This discussion is largely Sun/Solaris-centric, as well as highly Oracle-focused - but much of the information here may also be applicable to other brands and flavors or computing.

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For your reading pleasure, today I'm publicly posting a paper I wrote back in 2001 called "Oracle I/O: Supply and Demand". This paper was delivered at our Sun User's Performance Group (SUPerG) conference in Amsterdam in October of that year, but never made widely available to non-attendees. Though the paper is a little dated, it still represents my approach to explaining I/O in general. That is, what you measure with Oracle, iostat, or any other tool - will be the result of some demand factors constrained by some supply factors. Sounds simple, eh? I've found that illuminating both supply and demand factors - and showing how they interact - is the key to untangling the physics of any given situation. While the principle is simple, "the devil is in the details", and those details are continuously in flux!

If I ever write a book, this will be the basis for a chapter in it! I hope that making this paper available here will help others further their holistic understanding of disk I/O in general! This paper could be enhanced by discussion of other factors, including NFS, ASM, and RAC/grid factors for example - but I'm more likely to blog about such things than take a stab at a Grand Unified White Paper in the near future.

I'll never forget that trip to Amsterdam! It was just after 9/11. Air travel was rather tense, to say the least. SUPerG attendance from some parts of the world was severely impacted. Sadly, in the time since, Sun's SUPerG program has wound down. I have many fond memories from my SUPerG outings!

I'm proud to be part of the Performance and Applications Engineering (PAE) group at Sun Microsystems, where my clever colleagues continuously amaze me with their creative and diverse means of tackling the most challenging performance analysis tasks. My work centers on the performance of Sun's products and performance-related service delivery, and my activities are primarily clustered under our "Customer Focus" programs.

My traditional technical focus has been in the areas of Oracle and storage performance. In recent years, I've been quite involved in matters of service delivery where performance is involved. Since much of my career has consisted of "smoke jumping" exercises (a common industry term for flying into difficult situations and sorting them out), I've seen that most of what goes wrong in production are repeated patterns. After several years of flying around, I finally figured out that it is far less wearisome and higher-leverage to capture knowledge on paper than to wrestle cases one-by-one, so I turned to writing a while back.

Among my easier-to-find publications are the Sun Blueprints Online^TM publications "Sun/Oracle Best Practices" in 2001, and "Performance Forensics" in 2003. I also develop material for various performance-related training internal to Sun, and contribute to selected industry performance symposia.

In today's fast-evolving technology world, knowledge rots so quickly that is can be discouraging to try capturing it at a moment in time via whitepapers. Therefore, beginning now in January 2007, my Good Intentions are to make the occasional posting here in my blog or contribute some tidbits here and there on solarisinternals.com. Nobody should hold their breath waiting for me to post anything, but as of today, I've made a place in corporate cyberspace where my time-to-market can be minutes, not weeks or months!

Whether or not I span the generation gap and start blogging about my kids, cats, cars, or personal concerns is very much TBD!

ADDENDUM: One of the hot topics current in the Sun blogger community is the desire to add a "minor edits" feature to our blog engine to avoid pestering folks with RSS push traffic when bloggers correct typos or make minor phrasing changes. So, this post was my first, and this paragraph is no longer a "minor edit", I guess. My apologies to anyone who gets spammed by my minor edits until we get that sorted out.