What is Leap Second?
"The solar day is gradually getting longer because Earth's rotation is slowing down ever so slightly," says Daniel MacMillan of NASA's Goddard Space Flight Center in Greenbelt, Md. [Source] Due to these irregularities, the International Earth Rotation and Reference Systems Service (IERS) has implemented the leap second process, which can be introduced into UTC at the end of June or December, depending on the Earth's rotational status. The latest IERS bulletin can be found here: IERS Bulletin C (leap second announcements) - latest issue.
When a leap second is announced, there will be a one-second adjustment applied to Coordinated Universal Time (UTC) at the specified date and time.
When is the next leap second scheduled to occur?
The next leap second will happen at 2016 December 31, 23h 59m 60s.
Has this happened before?
Leap second was introduced in 1972 and has occurred on at least 27 occasions at the time of this publication.
How is Pure Storage preparing for leap second?
Pure Storage does not deadline schedule events based on the time of day. When there is a skip forward in time, the only effect will be on the timestamps in our logging. When we do care about ordering, we use monotonically increasing sequence numbers, instead of timestamps, so if a skip backwards in time did occur our logs would have overlapping timestamps that would be visible to us. Pure Storage systems use NTP so we have had many arrays adjust their time while running, and we have not seen any issues from these adjustments.
Pure Storage tests for leap second in-house to confirm these expectations.
Do the customers need to take any action to prepare for a leap second event on the Pure Storage FlashArray or FlashBlade?
Pure Storage is prepared for leap second events and there are no impacts to any Pure Storage products. No customer action is necessary.