[110412] in North American Network Operators' Group
Re: Leap second tonight
daemon@ATHENA.MIT.EDU (Marshall Eubanks)
Mon Jan 5 15:41:45 2009
From: Marshall Eubanks <tme@multicasttech.com>
To: Adrian Chadd <adrian@creative.net.au>
In-Reply-To: <20090105163051.GB18304@skywalker.creative.net.au>
Date: Mon, 5 Jan 2009 12:21:22 -0500
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Jan 5, 2009, at 11:30 AM, Adrian Chadd wrote:
> This begs the question - how the heck do timekeepers and politicians =20=
> get
> away with last minute time changes?
>
> Surely there's -some- pushback from technology related interest =20
> groups to
> try and get more than four weeks warning? :)
>
>
Having been involved in the leap second business, I can tell you that =20=
Daniel
Gambis strictly follows the rules, which are
Bulletin C is mailed every six months, either to announce a time step =20=
in UTC or to confirm that there will be no time step at the next =20
possible date.
If you want more lead time warning, pay attention to the LOD graph in
http://hpiers.obspm.fr/eop-pc/
The long term LOD offset is about 1 msec now. That means that every =20
day, Earth time and atomic time will drift off by 1 msec. Since there
are 1000 msec in the second, and since the rule is that a leap second =20=
is chosen when the difference (UT1=E2=88=92UTC) approaches 0.9 seconds, =20=
projected
out to the next period, and since the strong preference is to have =20
leap seconds in January, you can generally figure out what will happen =20=
before
Daniel announces it.
For example, in one year the offset should be ~ 400 msec, so I will =20
informally predict another leap second in January, 2011, not 2010.
Keep watching that graph.
Anyone who is dealing with Leap Second code should keep in mind that =20
negative leap seconds (i.e., no second # 59, instead of an extra =20
second called
60) are a distinct possibility. It all depends on the "weather" at the =20=
core mantle boundary - note that the LOD offset was almost 3 msec not =20=
too long ago.
Regards
Marshall
>
> Adrian
>
> On Mon, Jan 05, 2009, Frank Bulk wrote:
>> A report from a DHCP/DNS appliance vendor here:
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> Several customers have reported a complete lock-up of their Proteus =20=
>> system
>> around the beginning of January 1st 2009. We believe that we have =20
>> traced
>> this to a problem in the underlying kernel and NTP and the handling =20=
>> of the
>> date change associated with 2008 being a Leap Year and therefore =20
>> having 366
>> days.
>>
>> Several conditions must be met to trigger this problem:
>> 1. The Proteus was originally installed as v2.1.x or earlier.
>> 2. NTP is enabled as a client with 2 or more external source servers
>> defined.
>> 3. There is a discrepancy in the times reported back by these other =20=
>> NTP
>> servers.
>>
>> There is no correction available at this time, and the resolution =20
>> is to
>> power cycle the system, after which it will run fine.
>>
>> If you experienced a similar problem at the indicated time, please =20=
>> submit a
>> trouble ticket so that we can confirm that this occurred on your =20
>> system.
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>>
>> I don't know what the underlying OS is.
>>
>> Frank
>>
>> -----Original Message-----
>> From: Kevin Day [mailto:toasty@dragondata.com]
>> Sent: Wednesday, December 31, 2008 4:42 PM
>> To: NANOG list
>> Subject: Leap second tonight
>>
>>
>> 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=3D%22kevin+day%22+leap+seco=
nd+r
>> eminder+nanog&page=3D1&refer=3Dcnkxb3iv7sls5axu
>>
>> 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 =20
>> damage
>> I'd heard from anyone after that event was their clock being
>> significantly off for several hours.
>>
>> -- Kevin
>>
>>
>>
>
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