All staff members, in preparation for leap second 2015, should watch a brief training on the other problems with time & timezones[1].
[1] https://www.youtube.com/watch?v=-5wpm-gesOY
On Thu, Jun 25, 2015 at 12:05 PM Gabriel Wicke gwicke@wikimedia.org wrote:
Alex and Moritz,
thank you for taking care of this. These leap seconds are a real pain in the butt for time-based distributed systems, and I'm glad that we have a plan in place. I hope the movement to abolish leap seconds < https://en.wikipedia.org/wiki/Leap_second#Proposal_to_abolish_leap_seconds
wins out in the end!
On Thu, Jun 25, 2015 at 7:27 AM, Moritz Mühlenhoff moritz@wikimedia.org wrote:
- On the 1st of July we'll re-enable NTP in batches. System clocks will
move forward by a second once NTP is started again,
To clarify: By default, system time will move *backwards* one second.
We just talked about this on IRC, so just for other's benefit: With NTP's -x option we should be able to smear the adjustment (by slowing down the system clock temporarily) until the leap second is incorporated into the system time. This avoids non-monotonicity, which is important for systems that use time to capture causality. It would be great to apply the adjustment to all nodes of the cassandra cluster at once, so that their clocks are being slewed in lock-step.
Gabriel _______________________________________________ Wikitech-l mailing list Wikitech-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikitech-l