Then a miracle occurs (understanding vs. memorizing Systems Management)
Posted by Shane Corellian on Wed, Jun 16, 2010
Photo by Jean-Michel Folon
It still amazes me how many system administrators don't feel the need to understand the under-pinnings of Systems Management. I push a button and software gets installed on a remote computer. I run an inventory scan and suddenly I have a list of installed software.
I'm constantly reminded of the Sidney Harris cartoon "Then a miracle occurs". How did that software get installed? Where does SCCM extract the list of installed software on each machine? How does Admin Arsenal know if a laptop has a smart-card reader?
If I have a prayer of performing any meaningful troubleshooting when problems occur, then it is essential to understand the How, Where, and What of the my environment.
You can, very quickly, determine if a person troubleshooting a problem has a good understanding of their environment. If they don't understand what's going on under the hood, then their troubleshooting amounts to little more than memorization. If "problem A" occurs, then "solution A" is the answer. "See, it's clearly written in this KB article." But what happens when the correct answer isn't, in fact, "solution A" ? What happens when the problem doesn't even have a description in the knowledge base?
I know, for example, that Tivoli retrieves its Installed Software list from two sources: A) Data stored in the "Uninstall" key of the registry; and B) Signature data where software names, publishers and versions are mapped using a file name and its corresponding file size.
If some software that I am expecting to see listed as being installed doesn't show up in an inventory report, then I should know exactly WHERE (on the target computer) that data is supposed to be found. I will be able, therefore, to troubleshoot more effectively. If I know HOW the scanned data is expected to move from the registry of the target computer to its ultimate entry in a database, then I can more effectively determine when and where any errors are occurring during transit.
My next few blog posts will be about some of the under-workings of common systems management tools.
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