Posted by Daniel Waldron on June 29th, 2015
If you weren’t aware, there will be an additional leap second occurring on June 30, 2015. Is your NTP time server prepared? Galleon Systems answers some of the frequently asked questions about the upcoming leap second.
Will my NTP Time Server be disrupted by the leap second?
No, because NTP servers can implement a leap second by repeating the final second of the day. In particular, GPS NTP servers are very useful for preventing disruption.
If you’re using GPS NTP servers your system administrators can make provisions to adjust for leap seconds.
If you’re using a Linux operating system, its ntpd process should be able to pre-empt the leap second, preparing devices on your network 24 hours in advance of the changes.
Some devices on your network will make minor adjustments during the day, giving the appearance that 60 seconds has elapsed. Other devices will simply alter the time by a second once the leap second has taken place.
How does the leap second impact the time providing mechanism of my NTP servers?
The short answer is that the leap second will have no impact on the delivery of NTP. The technical answer is that the ntpd process receives notification from an attached reference clock. In the case of a Galleon time server this will be a GPS antenna.
As time must be seen to be monotonically increasing, a leap second is added with the sequence 23:59:59, 23:59:60, 00:00:00.
Despite the clock being halted during the event, any processes that query the system time cause it to increase slightly, which preserves the order of events.
Will there be any deviation in NTP data provided by my NTP server?
Any device requesting time from your server could be out by up to a second as the device acknowledges the leap second. However, this deviation will be rectified by subsequent requests.
Do I need to do anything to?
No, the NTP service will deal with the leap second. Any of your systems using NTP will make adjustments throughout the event.
Download our white paper
For a fully informative guide to the upcoming leap second, download Galleon Systems’ – ‘Leap Second Tutorial’ – white paper here.