Thermodynamics and Oracle Identity Manager
by Deborah Volk on March 18th, 2009

Long time ago in the land far away I was an avid student of physics . If you need a refresher course on social implications of physics and the difference between experimental and theoretical physics, consider watching a popular US show Big Bang Theory and you shall be enlightened.
Somewhere along the way I learned about thermodynamics, an area in physics that studies heat. Three laws of thermodynamics (we won't count the zeroth law or the wayward addition of reciprocal relations as another law) are the foundation of thermodynamics. The three laws postulate that energy can be exchanged between physical systems as heat or work and they also introduce a concept of entropy.

Most people are blissflully unaware of thermodynamics, entropy or when their mail gets delivered but they do know that "stuff always rolls downhill". Hey, that's 2nd law! The second law is all about entropy, essentially "chaos increases and you have to work to prevent it from happening." To be a tad more eloquent , I went to the ever-present Wikipedia and looked it up. On the page for the 2nd law was this: "In a system a process that occurs will tend to increase the total entropy of the universe". Let's be literal and liberal with this definition and see where we get if we apply the 2nd law to performance aspects of an Oracle Identity Manager (OIM) installation.
First, a system in the above definition is something that has a boundary. Within boundaries, the system does not interact with its surroundings and obeys conservation laws (total mass and energy stays the same). For the purpose of our dissertation, the system will be defined as two physical hardware boxes (an application server and a database) that have a fixed number of CPUs and a fixed amount of memory. These servers are neither aided by nor aid other servers in the environment, e.g. there's no cloud or grid so you can't expand or shrink the capacity of the servers and these machines are dedicated to hosting OIM. This way, the total computational power (or "energy") of our system remains constant.

Second, entropy is a measure of the unavailability of a system's energy to do work. In our case this means the server's ability to process instructions. As entropy goes up, then, by definition, the machine's ability to complete work goes down. Applying this to OIM we arrive at the 2nd law for Identity Management ( all rights reserved!) : In an installation of OIM with dedicated hardware, performance will decrease as more resource objects, workflow processes (provisioning and approval), scheduled tasks running reconciliations and so on are added to the system.

Now, this is all just common sense, but for those of us in the know with OIM, understand the true impact of this statement. The more processes you have, the more you have to work to keep the system running. Never underestimate the importance of performance tuning and the necessity of doing it BEFORE going into production.

Class dismissed!

Posted in Oracle Identity Manager    Tagged with oim, thermodynamics, performance


K. Brian Kelley - March 19th, 2009 at 8:09 AM
Of course, the conclusion is true with everything regarding computer, no just identity management. For instance, if you don't test to see what happens when your web site has 1,000 concurrent connections, you can't rightfully say what it will do when that day comes because there is a fixed amount of energy (processing power) for the website unless you choose to open the system (introduce more web servers) so that you can add more eneregy (processing power).

Deborah Volk - March 19th, 2009 at 11:55 AM
That's true, Brian. Perhaps my next blog should be about the difference between certain systems and their energy consumption patterns but I digress. I think we'll leave thermodynamics alone for a while!
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