Monday, October 04, 2010

Documentation, not always the How To Dos

Documentation for me is often just How to do something, but I have been forgetting the WHY part of the equation. For instance, my documentation says to do our weekly maintenance window after 21:30 and to only reboot one particular server after 21:45, but I didn't say why and had forgotten myself. So I started doing the maintenance earlier and at one point rebooted the one particular server at 21:30. This caused the last of our production cron jobs to not run, and thus a customer didn't get their batch for the day.

Now this could have been avoided a few different ways. Since that first time was a mistake any thing that happens after it is a failure on my part, and thus can't happen again.
  1. I could have followed our procedure to the T.
  2. Read my e-mail to see that the cron job hadn't run yet.
  3. Run the cron job by hand after the server restart.
  4. Did all of the precursor work and waited for the cron job to run.
  5. Did all of the precursor work and run the cron job by hand.
I have chosen to go with option 1, follow our procedure to the T. We started doing the weekly maintenance for a few reasons and it was to be done after 9:30, with that one particular server last to ensure this didn't happen. Now once again I have my WHY, and I have it written down so if I question it again I know why.

This is just one instance where the WHY is critical, but there are others. So please when you are writing documentation, and you should be please include the WHY you do something the way you do it. It also helps train the new guy, or your replacement.

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