| Re: [chrony-users] Sporadic NTP dropouts (bad maximum delay ratio and maximum delay dev ratio) |
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On Thu, May 28, 2015 at 07:06:27PM +0200, Ulrich Schwesinger wrote:
> I'm using chrony in client mode hooked up to a local NTP server. I get
> sporadic occurrences where NTP synch fails. I'm a bit unsure how to
> interpret the measurements.log file, and would appreciate any help.
>
> ========================================================================================================================
> Date (UTC) Time IP Address L St 1234 abc 5678 LP RP Score Offset
> Peer del. Peer disp. Root del. Root disp.
> ========================================================================================================================
> 2015-05-20 15:54:31 192.168.0.30 N 13 1111 111 1111 6 5 0.03 6.100e-05
> 7.540e-04 1.045e-06 0.000e+00 1.991e-01
> *2015-05-20 15:55:36 192.168.0.30 N 13 1111 110 1111 6 6 0.13
> 2.700e-04 1.270e-03 1.001e-06 0.000e+00 7.411e-02*
Failed test C means the round trip delay was significantly longer than
is usual with this peer and the measurement is ignored on the
assumption it has a large error. In the peer delay column you can see
the delay was 1.27 milliseconds which is larger than the previous
delay of 0.75 milliseconds. This is completely normal.
> *2015-05-20 16:05:53 192.168.0.30 N 13 1111 111 1111 5 5 0.00
> -1.912e+00 6.830e-04 2.408e-06 0.000e+00 7.948e+00*
> *2015-05-20 16:05:55 192.168.0.30 ? 16 1111 111 1001 5 5 0.00
> -1.912e+00 6.451e-04 2.350e-06 0.000e+00 0.000e+00*
> 2015-05-20 16:06:03 192.168.0.30 N 13 1111 111 1111 5 5 0.00 -1.911e+00
> 7.000e-04 2.440e-06 0.000e+00 7.948e+00
This is odd. It looks like the server lost its synchronization and
claims a very large root dispersion of 7.9 seconds. Also the local
polling interval is only two seconds here, was that a burst started
from chronyc or was chronyd restarted?
> I find this very hard to debug, is there any other thing I could do to find
> out what's exactly going wrong?
It would be useful to know what was happening on the server. On the
client side it looks ok to me.
--
Miroslav Lichvar
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