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Software Configuration Confusion |
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Monday, 04 December 2006 |
I often find that people confuse a software's configuration with the software itself. I believe this is because we are not disciplined enough in our use of terminology.
Consider a simple situation. I have a PC in front of me. I can describe this PC: a pentium 4 processor clocked at 3.2 Ghz, 2Gb RAM, 300Gb hard drive, and so on. This description is the PC's configuration. The PC is an instance of that configuration. No one (well, no one I know) would call the PC the configuration.
However, once we talk about software (or any other electonic asset) we get very messy about our use of the term "configuration". It is common to hear people describe a specific set of files on a file system as "the configuration".
The problem is that just as the PC is not the configuration, neither is any specific set of files on my file system "the configuration" of the software, it is merely an instance of the configuration. These file conform to the configuration.
What then is the configuration?
Generally we hold the configuration in our Definitive Source Library (DSL) and our Configuration Management Database (CMDB). The CMDB usually being closely tied to the DSL (if not a superset) - according to a specific organisation's setup.
The configuration contains the meta-data that describes the files, directories, documentation, etc. that make up the configuration items. It also contains copies of the file's content so that when requested a copy of the file's content can be provided to the user's filesystem. This is analogous to providing instructions for building the PC and ending up with a physical PC sitting on your desk - the instructions are the configuration, the PC is the instance.
Why is this distinction so important?
This distinction is important because when we discuss Configuration Management we are explcitly talk ing about the management of things in our CMDB/DSL. We are not talking about anything outside that system, other than to say that "yes, this conforms to configuration X" (audits).
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Last Updated ( Monday, 04 December 2006 )
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