All staff members, in preparation for leap second 2015, should watch a
brief training on the other problems with time & timezones[1].
[1]
On Thu, Jun 25, 2015 at 12:05 PM Gabriel Wicke <gwicke(a)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(a)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(a)lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikitech-l