I’ve been thinking about how to use my blog to describe different individuals who have helped me learn about Oracle performance tuning. I was thinking about having a single blog entry or page describing several people but have decided that will be too long and overwhelming to read or to write. So, I got the idea of writing about a single individual at a time. Now, the challenge about writing about someone is that this is only my perspective of them and I could have some details wrong. So, if there are any errors or negative implications then that is on me and no reflection on the individual I’m describing. I’m including this person because their work has helped me in my job as an Oracle DBA in the performance tuning area so the intent is to be positive and to encourage other people to benefit from their work. In most cases these individuals have free or inexpensive materials available that can be of great worth to an Oracle DBA who is working on tuning.
So, I’m starting with Craig Shallahamer because he was the first individual who really helped me learn about Oracle performance. I started as an Oracle DBA in December of 1994 while working with Campus Crusade for Christ. At CCC we migrated all of our applications off of a small IBM mainframe and on to an Oracle database running PeopleSoft applications. But, at some point our new donations system was having bad performance. It was slower than the mainframe system we had just replaced. A couple of managers in our IT area ran into Craig and connected him up with me. It ended up that we were saturating one of our disk arrays with random I/O while our other arrays were underutilized. Craig’s free papers on Oracle waits and the use of operating system monitoring utilities such as sar -d really helped me understand how to diagnose our disk I/O issues.
If you want to check out Craig’s resources go to his OraPub website. I have read several of his papers – most notably ones about Oracle waits and about response time/queuing theory. Also, I’ve learned from his free tool called OSM which records V$ table values and operating system tool outputs. Craig sells a new tool called Stori which I know he is excited about, and he has a number of other free tools as well. I haven’t been able to take one of his paid courses but I’ve read the materials for his firefighting class several years ago and it was very helpful. I also read Craig’s first book which is on forecasting performance.
It is hard to do justice to someone’s work and I’m not sure I’m explaining it that well. I think of Craig in terms of operating system/hardware, Oracle internals, waits, mathematical models, performance tuning theory. It has been helpful for me to just take one of his excel spreadsheets and play with the values and think about what the curve means in terms of queuing and performance. Most DBAs I know aren’t that comfortable with operating system utilities like sar and don’t know what values to look for. And, few people seem to understand queuing theory and other mathematical models of Oracle systems.
So, Craig is a good source for Oracle performance information that may not be readily available to the average DBA unless they know where to look. I hope others find his work as helpful in their jobs as I have.