Re: NTP sets clock backwards
From: Andreas Schulze (b79xan_at_gmx.de)
Date: 11/28/03
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Date: Fri, 28 Nov 2003 17:09:02 +0100
"Nick" <nick.skingle@ftid.com> schrieb im Newsbeitrag
news:ed7b1c4.0311280730.6a1b1381@posting.google.com...
> Is there any way to stop xntpd from setting the time backwards. I have
> heard there is an undocumented -x flag, but our ntp clients are within
> an SP environment and xntpd is started from the resource controller.
> Any comments and suggestions with regards to the way ntp keeps time
> would be appreciated
>
> Thanks
> Nick
Hallo Nick,
you did not write which oslevel you use. Thus some thoughts based on
assumptions only: AIX xntpd sets time backwards if time difference to time
server becomes >= 1 second. Problem is, that time is switched back in 'step'
(of full seconds). This leads to problems as then a program might end before
it started, e.g. if timestep back ocurred while program was running. You can
watch this in the system log. Great fun when using SAP or running certain
programs - NOT. The undocumented x-flag is not there. At least it was not
there with xntpd 3.4y (I stopped using AIX xntpd since).
So what to do? Solution is easy: get ntpd from http://www.ntp.org/
This ntpd (Ver. 4 or later) can 'slew' the time (by using the '-x' option
you mentioned) and replaces the AIX xntpd perfectly. I had to compile it and
did so with gcc. Worked perfectly for me.
# stopsrc -s xntpd
# The Subsystem xntpd was successfully requested to stop
# /usr/local/ntp4/bin/ntpd -x
Best thing is to start ntpd from /etc/inittab (with a sleep 1 between the
stop of xntpd and start of ntpd). Make sure , that only one ntpd is running.
Should you happen to have started ntpd after xntpd (e.g. both are up and
running) it is not enough to stop xntpd but you need to stop and start ntpd
again, too.
Search this group for further details.
HTH,
Andreas
- Previous message: Nicholas Dronen: "Re: java.net.SocketException: A system call received an interrupt"
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