[ntp:questions] Odd (mis)behavior when reference clock fails
unruh-spam at physics.ubc.ca
Tue Sep 23 20:05:48 UTC 2008
Steve Kostecke <kostecke at ntp.org> writes:
>On 2008-09-23, Kevin Oberman <oberman at es.net> wrote:
>>"Steve Kostecke" <kostecke at ntp.org> wrote:
>>> On 2008-09-23, Kevin Oberman <oberman at es.net> wrote:
>>> > [---=| Quote block shrinked by t-prot: 40 lines snipped |=---]
>>> >> It would be helpful to know the exact NTP version, and which
>>> >> hardware clock and refclock driver was used.
>>> > It's 4.2.4p4 running on FreeBSD 7.0. The reference clock is a
>>> > EndRun Tech CDMA clock using the TrueTime driver. When the system
>>> > was running, ntpq claimed no successful polls of the reference
>>> > clock or the PPS. It was getting good responses from other systems,
>>> > but not syncing to them.
>>> The ntpq peer billboard you posted shows that ntpd _has_ chosen
>>> another system as the sys_peer. See below.
>> Yes, that is quite clear.
>The sys_peer is the time source that this ntpd is "synced" to.
>>> > remote refid st t when poll reach delay offset jitter
>>> >TRUETIME(1) .CDMA. 0 l - 16 0 0.000 0.000 0.001
>>> >PPS(1) .PPS. 0 l - 16 0 0.000 0.000 0.001
>>> >-time1-owamp.es. .PPS. 1 u 17 64 177 2.058 -10.335 0.038
>>> >*time2-owamp.es. .PPS. 1 u 49 64 177 24.556 -10.408 0.020
>>> >-time3-owamp.es. .PPS. 1 u 63 64 176 55.640 -10.337 0.049
>>> >+time4-owamp.es. .PPS. 1 u 59 64 176 20.770 -10.405 0.058
>>> Is there something about this system which is different from the other
>>> time servers?
>> As stated, all of the servers are identical in terms of hardware and
>> software and configuration. The only differences in the ntp.conf is that
>> each system is missing the entry for itself.
>It is possible that there may a problem with this hardware. Does the
>clock always drift in the same direction? Do you see periodic clock
>steps? You may need to adjust the kernel's tick.
That is precisely what ntp is supposed to do for you.
Unless you are suggesting that the clock drift is greater than 500PPM. He
could look at the drift rate (adjtimex -p and look at the frequency.
The quoted one is in weird units.
It looks line frequency/14555 is PPM
If this is near 500 then you are introuble and have very bad hardware.
>Steve Kostecke <kostecke at ntp.org>
>NTP Public Services Project - http://support.ntp.org/
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