Misunderstood Midnight Maintenance Windows
by Chris Josephes
Technically, Midnight is the beginning of a new day. If you're used to military time, it's easier to understand, since you're starting over at 0000. But most people have always used Midnight in the context of a late evening, as in, I'm going to stay up until Midnight; so it's pretty common to accidentally associate it with the previous day.
To overcome confusion, we announce all Midnight maintenance windows as having a start time of 12:01 AM. It's close enough to Midnight, and for some reason, everybody seems to understand it. Sure, Midnight is ambiguous, but 12:01 on a Wednesday is clearly early understood as Wednesday morning. I'm not going to complain about a one minute compromise if it means avoiding ten minutes of writing emails to clarify the schedule.
It is for this reason that we generally schedule maintenance at 11pm or 1am (or later), depending on the time zone of the target systems.
You've got the right approach (12:01 AM) 'cause Midnight is ambiguous (and 12am and 12pm doubly so).
|This is only an ambiguity for idiots, and since there's no shortage of idiots in the world, this probably makes for a good policy.|
|Mark Leighton Fisher
|Insurance policies (the ones I have seen) always start at 12:01am or 12:01pm just to avoid this kind of confusion. (Interesting that the NIST thinks so too.)|