[ntp:questions] Leap Second on NTP server at stratum 2

Kashif Mumtaz Tahir ktahir at ies.etisalat.ae
Thu Jun 11 06:41:31 UTC 2015


Dear Jochen,
You extracted description is right , we are at stratum 2 and just syncing
its time with stratum 1 level GPS device.

Litte bit confused with your conclusion. When leap second will happen on GPS
what will the impact on our stratum 2 level server and below beyond ( Straum
3 client etc )


Regards,

kashif


-----Original Message-----
From: Jochen Bern [mailto:Jochen.Bern at LINworks.de] 
Sent: Wednesday, June 10, 2015 6:43 PM
To: Kashif Mumtaz Tahir
Cc: questions at lists.ntp.org
Subject: Re: Re: [ntp:questions] Leap Second on NTP server at stratum 2

On 06/10/2015 01:27 PM, Kashif Mumtaz Tahir wrote:
> Dear Macro,
> We just want to sync seamless with leap seconds. [...]
> Should we need to change/tune anything.

I read your description as:
-- There is a GPS device that actually *speaks NTP* (as opposed to,
   e.g., being connected to a server with a serial cable)
-- This device feeds a central stratum 2 server running ntpd
-- Everything else of interest is an NTP (not SNTP) client of
   that central server
-- No special configs beyond the above, in particular,
   -- no additional external NTP servers,
   -- no leap seconds file, and
   -- no suppression of stepping
   configured on any of the machines.

My conclusions:
-- Whatever announcement the GPS unit makes of the upcoming leap second
   will be forwarded to the various machines.
-- You hopefully have historic records, vendor statements, or whatever
   indicating that this GPS unit *will* announce a leap second to be
   *inserted*.
   (It mistakenly announcing a *negative* leap should be highly
   improbable, but I have no idea how likely it is to find a GPS unit
   that flat out doesn't propagate leap second announcements.)
-- The job of actually "executing" the leap second will be left to the
   OS kernel of every individual machine - if you cannot afford them
   hitting a historic or new bug that night, you should start testing
   kernel versions with simulated leap seconds ASAP.
-- There is a (very small) chance that in the leap second night, your
   single-point-of-failure GPS unit will somehow cease to work before
   any announcement happens and your platform will never learn of the
   upcoming leap second - in which case you'll find it working but
   being offset by one second in the morning.

Regards,
								J. Bern
-- 
*NEU* - NEC IT-Infrastruktur-Produkte im <http://www.linworks-shop.de/>:
Server--Storage--Virtualisierung--Management SW--Passion for Performance
Jochen Bern, Systemingenieur --- LINworks GmbH <http://www.LINworks.de/>
Postfach 100121, 64201 Darmstadt | Robert-Koch-Str. 9, 64331 Weiterstadt
PGP (1024D/4096g) FP = D18B 41B1 16C0 11BA 7F8C DCF7 E1D5 FAF4 444E 1C27
Tel. +49 6151 9067-231, Zentr. -0, Fax -299 - Amtsg. Darmstadt HRB 85202
Unternehmenssitz Weiterstadt, Geschäftsführer Metin Dogan, Oliver Michel



More information about the questions mailing list