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Super User
Time Change

While backing up a server today, I noticed a huge number of changed files that I didn't touch. I eventually decided my provider had updated part of the OS for me. I wondered if the server was out of service for the update, so I loaded a log file that is recording a temperature reading every 20 minutes, looking for a gap. I didn't find a gap, but I did see a tiny glitch in an almost straight line. It is zoomed in a lot below, I almost ignored it.


2AM glitch, first Sunday in November (or whatever the current rule is.)2AM glitch, first Sunday in November (or whatever the current rule is.)


That's the repeat of the 1AM to 2AM hour for the "fall back" time change.


  • If you care, record UTC time, not local time
  • always use a graph to visualize your data
  • wow--the rise and fall is more asymmetrical than I thought. It is more useful to me for the time to be local time so the data is easily understood. I'm 4 or 5 hours away from UTC.


I'm guessing the next time I reboot the server I'll get the changes. Or maybe the entire update fit inside the 20 minute cycle.

Last Modified: Nov 17, 2020 8:37 PM