Re: [ntp:questions] Slow sychronization
Ulrich Windl writes: >"Ray" writes: >> Hi All, >> >> I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux >> machine with kenel version 2.6.27. >Hi! >I didn't investigate further, but I see the same effect, and I suspect >that there is a mismatch between the kernel interface and ntpd. I'm >running several instances of SLES10 SP2 here. Nope. ntp simply has very slow response to errors. Its time constant is a bit over an hour at poll level 6. (ie it decreases the error by about a factor of 2 every hour or so, but there is an overshoot at first.) >> >> When I start the daemon, the peer information shows that all the peer have a >> offset of about 30 milliseconds. This offset will increase to about 50 >> milliseconds after an hour. It might take many hour to days before the >> offset comes down to a few milliseconds. I tried using 'iburst' on the peers >> to see if this would speed things up, but it made no difference. >> >> Are there any settings to speed up this process? Is the a problem with this >> version of NTP? >I'd fiddle with "minpoll" ;-) >> >> Thanks, >> Ray >> - ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Slow sychronization
"Ray" writes: > Hi All, > > I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux > machine with kenel version 2.6.27. Hi! I didn't investigate further, but I see the same effect, and I suspect that there is a mismatch between the kernel interface and ntpd. I'm running several instances of SLES10 SP2 here. > > When I start the daemon, the peer information shows that all the peer have a > offset of about 30 milliseconds. This offset will increase to about 50 > milliseconds after an hour. It might take many hour to days before the > offset comes down to a few milliseconds. I tried using 'iburst' on the peers > to see if this would speed things up, but it made no difference. > > Are there any settings to speed up this process? Is the a problem with this > version of NTP? I'd fiddle with "minpoll" ;-) > > Thanks, > Ray > - ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Slow sychronization
"Richard B. Gilbert" writes: >Ray wrote: >> Hi All, >> >> I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux >> machine with kenel version 2.6.27. >> >> When I start the daemon, the peer information shows that all the peer have a >> offset of about 30 milliseconds. This offset will increase to about 50 >> milliseconds after an hour. It might take many hour to days before the >> offset comes down to a few milliseconds. I tried using 'iburst' on the peers >> to see if this would speed things up, but it made no difference. >> >> Are there any settings to speed up this process? Is the a problem with this >> version of NTP? >> >> Thanks, >> Ray >> - >> >> >The topic has been visited several times in the last year or two. The >only solution I know of is to let ntpd run continuously. If, for any >reason, you need to shut down and reboot regularly, ntpd is probably a >poor choice. >There is software available called "chrony" which provides >"gratification now". I am uncertain as to whether it provides the same >accuracy as ntpd. In my tests, it provides about a factor of 2 better accuracy than does ntpd. It runs on Linux and BSD. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Slow sychronization
Ray wrote: > Hi All, > > I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux > machine with kenel version 2.6.27. > > When I start the daemon, the peer information shows that all the peer have a > offset of about 30 milliseconds. This offset will increase to about 50 > milliseconds after an hour. It might take many hour to days before the > offset comes down to a few milliseconds. I tried using 'iburst' on the peers > to see if this would speed things up, but it made no difference. > > Are there any settings to speed up this process? Is the a problem with this > version of NTP? > > Thanks, > Ray > - > > The topic has been visited several times in the last year or two. The only solution I know of is to let ntpd run continuously. If, for any reason, you need to shut down and reboot regularly, ntpd is probably a poor choice. There is software available called "chrony" which provides "gratification now". I am uncertain as to whether it provides the same accuracy as ntpd. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Slow sychronization
Ray wrote: > Hi All, > > I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux > machine with kenel version 2.6.27. > > When I start the daemon, the peer information shows that all the peer have a > offset of about 30 milliseconds. This offset will increase to about 50 > milliseconds after an hour. It might take many hour to days before the > offset comes down to a few milliseconds. I tried using 'iburst' on the peers > to see if this would speed things up, but it made no difference. I've seen same on NetBSD and FreeBSD and took it as normal on a fresh install with large swings in offset until a reasonable value for drift has been obtained. If you're lucky, a new kernel doesn't cause a significant change from existing driftfile value and sync will be quite rapid. Other point mentioned in the 500ppm thread is that if the drift value is large not only will it take a long period to sync, it may also not be possible at all for ntp to adjust to a reasonable offset or worse the offset will become unstable and swing wildly. Here, with a small value of drift, a few ppm, or maybe an established driftfile with larger frequency offset (but < 50ppm), I'd expect time offset to be within a few ms after a couple of hours or so assuming delay from sources is reasonably steady. "ntpdc -c loopinfo" gives following for my three servers: pc:k6-400 p4-2400via-c3-600 ntpd version: 4.2.0-r4.2.4p24.2.4p2 offset(ms):-0.00180.37 -0.000336 frequency(ppm):-0.876 8.868 -49.225 offsets taken at 30min split into ranges <.1ms <.2ms <.5ms etc 95%range(ms): <5 <5 <10 David > > Are there any settings to speed up this process? Is the a problem with this > version of NTP? > > Thanks, > Ray > - > > ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Slow sychronization
Ray wrote: > Hi All, > > I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux > machine with kenel version 2.6.27. > > When I start the daemon, the peer information shows that all the peer have a > offset of about 30 milliseconds. This offset will increase to about 50 > milliseconds after an hour. It might take many hour to days before the > offset comes down to a few milliseconds. I tried using 'iburst' on the peers > to see if this would speed things up, but it made no difference. > > Are there any settings to speed up this process? Is the a problem with this > version of NTP? > > Thanks, > Ray > - > > Ntpd will keep your clock well synchronized but it requires many hours to reach that state following a cold start. Performance is somewhat better after a warm start. For best results, start ntpd ten to twelve hours before you need tight synchronization. Let it run continuously as long as you need it. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
[ntp:questions] Slow sychronization
Hi All, I am running a new version of the NTP daemon, version 4.2.4p6, on a Linux machine with kenel version 2.6.27. When I start the daemon, the peer information shows that all the peer have a offset of about 30 milliseconds. This offset will increase to about 50 milliseconds after an hour. It might take many hour to days before the offset comes down to a few milliseconds. I tried using 'iburst' on the peers to see if this would speed things up, but it made no difference. Are there any settings to speed up this process? Is the a problem with this version of NTP? Thanks, Ray - ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
