[ntp:questions] ntpd doesn't set system time

Steve Kostecke kostecke at ntp.org
Wed Sep 12 20:42:29 UTC 2007


On 2007-09-11, Michael Nelson <mnelson at inc21.com> wrote:

> Laurent Monnoye wrote:
>
>> ntpd doesn't seem to set system time continuously.

The peer billboard included shows why very clearly. In this case ntpd
has _not_ selected "timeserver" as its sys_peer (note the absence of the
expected asterisk in the first column before "timeserver").

>> the offset between the local server and reference time server keeps
>> the growing (almost 0.5 sec / hour):

The Undiciplined Local Clock (.LOCL.) by itsself does not provide a real
time source to ntpd. 

Unless "timeserver" is using some unrevelaed external method of
disciplining its clock, we can only assume that it is free running.
This could very well be why ntpd has not found "timeserver" to be a
suitable source.

Would it be possible to use properly configured time servers?

>> # ntpq -p
>>  remote      refid  st t when poll reach  delay   offset  jitter
>> ================================================================
>>  timeserver  .LOCL.  1 u   47   64  377   0.150  -389.69  38.104

If this ntpd was synced to "timeserver" you would see an asterisk (*)
before timeserver.

The fact that the "timeserver" claims to be at stratum-1 adds nothing to
its quality or believability as a time source. And this could cause
problems in the future if "timeserver" is ever connected to another
network.

>> Any idea how to force ntpd to keep local system time in sync?

Provide ntpd with a suitable number of properly synchronized time
sources.

> I hope you get an answer, as I have been troubleshooting this on a SuSE 
> 10.2 box for a week or so.  Right now I have abandoned ntpd and just set 
> up a cron job to run ntpdate once an hour.

NTP is designed to synchronize clocks to a time base over a network.
The most commonly used time base is UTC, but others may be used. UTC is
cheap and ubiquitous; it may be easily obtained from other time servers
over a network or via services such as GPS, WWVB, various HF radio
stations, ACTS (via modem) and so on. Locally generated time bases of
high quality are usually a much more expensive route to take.

In simplistic terms, NTP synchronizes clocks by determining which time
source is most believable and then adjusting the clock frequency to
bring the clock as close as possible to that time source.

Please start another thread describing your problem and include your
ntp.conf (without the comment lines), and the output of 'ntpq -crv'.

-- 
Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/




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