Wednesday, June 24, 2015

VMware and the Leap Second




What is Leap Second ?
Nowadays do you even remember that Earth’s rotation around it’s own axis determines the length of a day or 24 hours (close enough) ?!?!

The thing is, Earth’s rotation is slowing down, very slowly, that means the leght of a day is not a precise 24 hours. Since we use Atomic clocks to synchronize time around electronic devices and those Atomic clocks are damn accurates, from time to time there's  a difference between them. When this difference approaches 0.9 seconds a +1 second is added to UTC, last time it occurred was on June 30, 2012.

So on Jun 30, 2015 23:59:60 UTC a leap second will be added.

Pay attention: It will be added at UTC time zone, if you are on a different zone, the change will occurs at another time of the day, example: on EST it will occur at 19:59:60.

Now that you understand what Leap Second is, let’s see how it does impact VMware’s products.

First and most important, it will only, potentially, affect systems that are configured to receive time synchronization from NTP server, so I assume everything is affected.
If you are not using NTP for synchronization, start remediating it NOW.

Second, it depends of how the operational system handles the Leap Second adjustment and each one will handle that differently.

There’s a common sense that you should change your NTP to slew mode, which will not make huge adjustments on it’s own time and will compensate the Leap Second progressively.

VMware’s has created a KB2115818 with all affected systems and how you address it on every one of them.

Also there’s a KB2121624 which shows systems not affected by the Adjustment.

Here's a link If you are interested on learn more on Leap Second.

And if you are wondering if it still make sense measuring our time based on Earth’s rotations here’s another one.





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I’m and IT specialist with over 15 years of experience, working from IT infraestructure to management products, troubleshooting and project management skills from medium to large environments. Nowadays I'm working for VMware as a Senior Consultant, helping customers to embrace the Cloud Era and make them succefully on this journay. Despite the fact I'm a VMware employee these postings reflect my own opnion and do not represents VMware's position, strategies or opinios.

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