[ale] Issues with NTP - synchronizes, then falls behind...

[jim.kinney at gmail.com (Jim Kinney)]

You need a new motherboard. Or some time with a soldering rig and a
new clock chip.

When the clock is drifting that fast ntp refuses to update it.
Multiple time jumps cause problems when they are greater than a second
or two.

On Sun, Jul 26, 2009 at 11:57 AM, Chris Woodfield<rekoil at semihuman.com> wrote:
> Hi,
>
> Having a major problem with a server that's running Debian 4.0 - can't
> seem to keep the clock in sync.
>
> I believe that the root cause is that my motherboard's hardware clock
> is running slow, but I'm trusting that ntpd should correct for that -
> which it is not.
>
> When I start ntp up, it connects to multiple pool.ntp.org servers, and
> appears to properly synch up the internal clock. However, within a few
> minutes, that clock is several seconds behind - what's more is that
> ntp seems to detect this, as shown in the offset field of ntpq -p, but
> doesn't seem interesting in correcting it.
>
> As the diag shows below, I'm skewing a full 10 seconds within 10
> minutes - is this just too far of a delta for ntp to be able to work
> with? If so, is there a config option to resolve this?
>
> Here's a quick shell script I wrote to demonstrate the problem -
> 192.168.0.155 is a Mac that syncs to time.apple.com.
>
> --
> echo -n "Initial Localtime: "
> date
> echo -n "Initial RemoteTime: "
> ssh 192.168.0.155 date
> sudo /etc/init.d/ntp restart
> for VAR in 1 2 3 4 5
> do
> ?sleep 90
> ?ntpq -p
> ?echo -n "Localtime: "
> ?date
> ?echo -n "Remotetime: "
> ?ssh 192.168.0.155 date
> done
> --
>
> And the output - note that on first run, it goes from 6 seconds behind
> before ntp restart to ~2 seconds, but then drifts out to a full 10
> seconds behind at the end of the 450 seconds it takes the script to run.
>
> rekoil at tino:~$ sh ntp_run
> Initial Localtime: Sun Jul 26 11:45:34 EDT 2009
> Initial RemoteTime: Sun Jul 26 11:45:40 EDT 2009
> Stopping NTP server: ntpd.
> Starting NTP server: ntpd.
> ? ? ?remote ? ? ? ? ? refid ? ? ?st t when poll reach ? delay
> offset ?jitter
> =
> =
> =
> =
> =
> =
> ========================================================================
> ?host2.kingrst.c 173.14.47.149 ? ?2 u ? 41 ? 64 ? ?1 ? 50.214
> 844.062 ? 0.001
> ?mainframe.cynac 216.218.254.202 ?2 u ? 27 ? 64 ? ?1 ? 31.627
> 1142.33 ? 0.001
> Localtime: Sun Jul 26 11:47:13 EDT 2009
> Remotetime: Sun Jul 26 11:47:15 EDT 2009
> ? ? ?remote ? ? ? ? ? refid ? ? ?st t when poll reach ? delay
> offset ?jitter
> =
> =
> =
> =
> =
> =
> ========================================================================
> ?host2.kingrst.c 173.14.47.149 ? ?2 u ? ?3 ? 64 ? ?7 ? 49.684
> 2195.19 1354.11
> ?mainframe.cynac 216.218.254.202 ?2 u ? 51 ? 64 ? ?3 ? 31.627
> 1142.33 1393.21
> Localtime: Sun Jul 26 11:48:43 EDT 2009
> Remotetime: Sun Jul 26 11:48:47 EDT 2009
> ? ? ?remote ? ? ? ? ? refid ? ? ?st t when poll reach ? delay
> offset ?jitter
> =
> =
> =
> =
> =
> =
> ========================================================================
> ?host2.kingrst.c 173.14.47.149 ? ?2 u ? 28 ? 64 ? 17 ? 49.684
> 2195.19 1922.28
> ?mainframe.cynac 216.218.254.202 ?2 u ? 14 ? 64 ? 17 ? 31.310
> 3886.57 1925.79
> Localtime: Sun Jul 26 11:50:13 EDT 2009
> Remotetime: Sun Jul 26 11:50:19 EDT 2009
> ? ? ?remote ? ? ? ? ? refid ? ? ?st t when poll reach ? delay
> offset ?jitter
> =
> =
> =
> =
> =
> =
> ========================================================================
> ?host2.kingrst.c 173.14.47.149 ? ?2 u ? 52 ? 64 ? 37 ? 49.684
> 2195.19 2647.40
> ?mainframe.cynac 216.218.254.202 ?2 u ? 38 ? 64 ? 37 ? 31.310
> 3886.57 2153.12
> Localtime: Sun Jul 26 11:51:43 EDT 2009
> Remotetime: Sun Jul 26 11:51:51 EDT 2009
> ? ? ?remote ? ? ? ? ? refid ? ? ?st t when poll reach ? delay
> offset ?jitter
> =
> =
> =
> =
> =
> =
> ========================================================================
> ?host2.kingrst.c 173.14.47.149 ? ?2 u ? 16 ? 64 ?177 ? 48.996
> 8992.49 5287.44
> ?mainframe.cynac 216.218.254.202 ?2 u ? ?2 ? 64 ?177 ? 31.310
> 3886.57 3275.18
> Localtime: Sun Jul 26 11:53:14 EDT 2009
> Remotetime: Sun Jul 26 11:53:24 EDT 2009
>
> Relevant config stuff:
>
> root ? ? 22986 ?0.0 ?0.1 ? 5492 ?1692 ? ? ? ? ?Ss ? 11:45 ? 0:00 /usr/
> sbin/ntpd -p /var/run/ntpd.pid -u 0:0 -g
> By default Debian 5 runs ntp as UID ntp, changed to root to eliminate
> potential permissions issues...
>
> from ntp.conf:
> server 0.debian.pool.ntp.org iburst dynamic
> server 1.debian.pool.ntp.org iburst dynamic
>
> Thanks,
>
> -Chris
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>



-- 
-- 
James P. Kinney III
Actively in pursuit of Life, Liberty and Happiness