topic Re: ntp sync in Operating System - HP-UX

ntp sync

prashanth — Tue, 01 Jan 2013 13:00:55 GMT

Dear All ,

We have recived the NTP related alert on 31 Dec 12 night .

xntpd[2279]: Unsynchronized, possible remote server failure or defective hardware clock

when i chekced the syslog

Oct 20 11:55:56 sxpx123 xntpd[1959]: tickadj = 625, tick = 10000, tvu_maxslew = 61875
Oct 20 11:55:56 sxpx123 xntpd[1959]: precision = 7 usec
Oct 20 12:00:46 sxpx123 xntpd[1959]: synchronized to 172.19.19.30, stratum=7
Jan 1 00:00:01 sxpx123 xntpd[1959]: leap second occurred, stepped time back 1 second
Jan 1 02:29:27 sxpx123 xntpd[1959]: synchronisation lost
Jan 1 02:41:37 sxpx123 xntpd[1959]: synchronized to 172.19.1.30, stratum=7
Jan 1 02:41:38 sxpx123 xntpd[1959]: time reset (step) 1.030062 s
Jan 1 02:41:38 sxpx123 xntpd[1959]: synchronisation lost
Jan 1 02:46:58 sxpx123 xntpd[1959]: synchronized to 172.19.19.30, stratum=7

after that is ysnchronised. So acn one help me to undetstand it . The alert which we got (xntpd[2279]: Unsynchronized, possible remote server failure or defective hardware clock) because of only (an 1 00:00:01 sxpx123 xntpd[1959]: leap second occurred, stepped time back 1 second)

Thanks!!!

Re: ntp sync

Bill Hassell — Wed, 02 Jan 2013 02:13:55 GMT

A leap second is occasionally inserted into the world-wide clocks to compensate for the slightly longer time of the earth's rotation. Here's a couple of references:

http://en.wikipedia.org/wiki/Leap_second
http://www.timeanddate.com/time/leapseconds.html

NTP assumes that a properly operating time source will not suddently jump without notice. It turns out that the NTP protocol does have a mechanism for handling a leap second:

http://support.ntp.org/bin/view/Support/ConfiguringNTP#Section_6.14.

However, it appears that HP-UX/xntpd does not do anything with the leap second. As such, you'll see the out-of-sync message which then be corrected like any out of sync condition.

Here are a couple of discussions about HP-UX NTP and leap seconds:

http://h30499.www3.hp.com/t5/General/HP-Support-Statement-for-XNTPD-Leap-Second-Processing/td-p/3663790

http://h30499.www3.hp.com/t5/System-Administration/HP-UX-and-Tru64-leap-second-handling/td-p/5609135

So your system is fine. The pertubation was corrected automatically.

Re: ntp sync

prashanth — Thu, 03 Jan 2013 11:01:37 GMT

Thank you much for your support and explaination

Regards,

prashanth