Bob Plankers of The Lone Sysadmin fame, has an excellent article titled Midnight is Always Tomorrow, which talks about communicating maintenance windows effectively with peers, as well as customers. He describes the confusion between the term of Midnight, and how some people consider it one day, whilst others see it as a different day.
Midnight is 00:00, meaning the start of a new day. Always.
If you’re in doubt, use 00:01. Assume everybody is clueless about time, because they are. For example, a lot of people think in terms of when they go to sleep, not what actual time it is, so if they’re still up at 0200 on Sunday they consider it to be Saturday.
He timed it well, I was thinking of posting about this very subject myself after a similar incident last week. After our QA team had cleared a break-fix release, it was scheduled for that fateful time, on Midnight on Friday. This was discussed at length by several people on Monday. After several meetings, I hear somebody walking past, telling the business units on Wednesday…
Yes, it’ll be released tonight, and ready for tomorrow.
“Tonight” would have been Wednesday night, tomorrow would have been Thursday. Somehow the magical shift of midnight pushed the release forward a day. Fortunately we interjected, and had them corrected.
This isn’t the only incident that is like this, we see it frequently when something gets requested for that time. I cannot begin to count the number of times I’ve had somebody ask me “is the release tonight at 2am?”. This goes into the idea that people consider “tonight” to be anytime before they went to sleep.
Going with Bob’s suggestion, use dates, and 24 hour clocks, if necessary (and always recommended) shift the time by a few minutes to make it obvious which date midnight falls on. Notify customers, tell them the outage/maintenance/changes are at 00:05 on 06/15/2010 (if you work with international customers, use words instead of numbers).
Bob finishes on a perfect example…
“The system shutdowns will commence at 2200 on 4/17/2010, the power will be disconnected at 0000 on 4/18/2010, and power-ups will occur again at 0800 on 4/18/2010. All times are in CDT (-0500).”
Be clear. Be concise. Be exact. Remove as much ambiguity as you can. The customers will be happy for it.