Leap second tonight

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From: Kevin Day <toasty@dragondata.com>
Date: Wed, 31 Dec 2008 16:41:39 -0600

Just a reminder that there's a leap second tonight.

Last time I watched for what happened on 01/01/2006, there was a
little bit of chaos: http://markmail.org/message/cpoj3jw5onzhhjkr?q="kevin+day"+leap+second+reminder+nanog&page=1&refer=cnkxb3iv7sls5axu

I've been told that some of the causes of these problems are fixed on
any reasonably recent ntp distribution, but just in case, you might
wanna keep an eye out if you're seeing any weirdness. The worst damage
I'd heard from anyone after that event was their clock being
significantly off for several hours.

While I hope people are not still running NTP versions too old to handle
leap seconds correctly, but that is only a small part of the problem. If
the stratum 1 reference clocks don't handle leap seconds correctly,
there is no way for NTP to deal with it.

We use CDMA clocks and last leap second it took weeks for all of the
cell sites to adjust the last one. As a result, I have set all of our
clocks for manual leap second and set them to adjust tonight at midnight
(UTC).I'll take a look in about 35 minutes and see how it worked.

I've heard reports of various GPS clocks not dealing with the leap
second correctly, as well. Fortunately, not too many need this sort of
accuracy, but those of us who do need to be prepared.

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Chiming in a little late here ...

Over at the NTP Pool we had about 9% of the servers not handle the leap second accurately; starting at midnight UTC. After an hour (so between 01:00 and 02:00) it was down to about 3%; a couple hours later down to about 1% of our servers (a few dozen)[1]. Most of those got in order within 24-48 hours. Interestingly the few who didn't get corrected within a few days were, tada: CDMA clocks.

To stay vaguely NANOG on-topic: I believe at least some of our ~1700 NTP servers are routers; so I'm guessing they handled the leap second alright.

Sounds like a "RISKS" lesson: Don't use side-effects of a tool for something critical. (If I understand it right then CDMA uses accurate time because it needs accurate frequency; not because it cares what time it is).

Also: Who came up with having the leap second on New Year!? Clearly not someone with any operational experience.

  - ask

[1] http://fortytwo.ch/mailman/pipermail/timekeepers/2009/004619.html and http://fortytwo.ch/mailman/pipermail/timekeepers/2009/004623.html

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Oh, quiet. After all, what's 6.5 million seconds or so between friends?

-j