[ntp:questions] Initial sync on starting ntpd with 20-21 minute time difference

Mike Cook michael.cook at sfr.fr
Wed Sep 26 07:13:07 UTC 2018


Karen,

> Le 24 sept. 2018 à 12:19, Karen Austin <Karen.Austin at kcom.com> a écrit :
> 
> Hi,
> 
> We have a RH 6.8 server with ntpd installed, but not currently running.
> 
> The time on this server is showing around 20-21 minutes ahead.
> 
> The server has been restarted and the messages log shows a successful ntpd start, but it is no longer running.

This is normal as ntpd will bail out if the initial difference between the reference server and local clock is greater than 1000 seconds, or 16mins 40secs.
So if you restart the daemon it will just exit as before. 


> 
> I would like to attempt to manually start the daemon but am concerned that the local time will then 'jump' to the correct time, which may affect applications on the server.
> 

You could override this protection mechanism by using startup option -g , but the local clock will step to the correct time, with possible application issues. There is an option -x to prevent steps on time differences greater than 128ms, but the max time difference accounted for is 600s, which is too small for your issue.

Before restarting ntpd you could use ntpdate to set the clock using the -B option to slew, rather than step, the clock to the correct time before restarting ntpd, but your offset is so large (1260 secs), that this may take a long time to complete.

On an Arm/Linux system I have I did a test with your offset and my clock is slewing at a little over 0,025 secs per minute, so the correction will need around 14 hours to complete.

Mike


> Can anyone confirm that the time will sync gradually?
> 
> Many thanks
> 
> 
> 
> 
> 
> 
> This email has been scanned for all viruses.
> 
> Please consider the environment before printing this email.
> 
> The content of this email and any attachment is private and may be privileged. If you are not the intended recipient, any use, disclosure, copying or forwarding of this email and/or its attachments is unauthorised. If you have received this email in error please notify the sender by email and delete this message and any attachments immediately. Nothing in this email shall bind the Company or any of its subsidiaries or businesses in any contract or obligation, unless we have specifically agreed to be bound.
> 
> KCOM Group PLC is a public limited company incorporated in England and Wales, company number 02150618 and whose registered office is at 37 Carr Lane, Hull, HU1 3RE.
> 
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions

People have only as much liberty as they have the intelligence to want and the courage to take.

Emma Goldman



More information about the questions mailing list