[ale] Unrelated... Re: Time jumping forward on RHEL6.3

Michael H. Warfield mhw at WittsEnd.com
Tue Nov 20 13:36:56 EST 2012


Totally unrelated but...

There seems to have been an anomaly yesterday in ntp.  I got word and
then saw on the NANOG mailing list that there was a time warp out of
tick and tock at usno.navy.mil.  The servers were reporting the year as
2000.  This has caused some impact on networks and servers that rely on
them, including time.microsoft.com.  It's been reported on NANOG that
this caused AD disrruptions in some cases and caused some ntp servers to
fail out.  If you have been relying heavily on Tick.usno.navy.mil or
Tock.usno.navy.mill (Tycho.usno.navy.mill is unknown as are the other
public stratum 1's) you should probably check the status of your time
and your ntp server.  You should also consider diversifying your time
references as well.

Regards,
Mike

On Tue, 2012-11-20 at 16:26 +0000, Lightner, Jeff wrote:
> Last week I noticed the time on two new servers we installed with
> RHEL6.3 had jumped forward even though we had ntpd running and use
> local time sources here.  I reconfigured ntp then with RedHat’s GUI
> for same then verified the hwclock was updated (and not using UTC)
> then for good measure rebooted both to make sure the system time was
> still correct.
> 
> Yesterday morning I had set myself a reminder to re-verify and time
> was still OK on both servers.  I again rebooted to verify the system
> time was set properly on boot.
> 
> We were installing new software and it suggested adding the “-x”
> option to ntpd which we did and restarted ntpd.   I again verified
> time was still ok after that.
> 
> Last night I noticed that at some point the time had again leapt
> forward as it had last week.   This was by about 9 hours and 14
> minutes.   It appears ntpd aborted (presumably due to the –x option
> that prevents skewing) due to large gap in time (720000).
> 
> This morning both servers are ahead by about 20 hours on system time
> even though ntpd has not been running since yesterday’s abort.
> 
> I’ve looked through all cron and anacron files and can’t find anything
> that would be setting time automatically.
> 
> A ticket has been opened with RedHat support but I’m wondering if
> anyone has seen something like this and has any ideas what might be
> causing it or how to prevent it.  We’ll be running cluster software on
> these two nodes so having time synchronizes is especially important.
> 
> We do run many other RHEL (4, 5 & 6) servers as well as HP-UX and
> Windows servers and workstations all using our internal time devices
> as the NTP time source so I’m mystified as to why these two servers
> have the issue.
> 
> 
> 
> 
> 
> 
> 
> 
> 
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-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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