On 2011-03-17, Gautam Thaker <gautam.h.tha...@lmco.com> wrote: > I have a stable drift value on my fedora 12 node and everything is > running well. (offsets are well below 1msec). If I now stop 'ntpd' > will my time start to drift relative to the 'correct time' by the PPM > value in the drift file?
The value in the "drift file" is a snapshot of the frequency correction being applied to the system clock. The contents of the drift file are updated approximately hourly. The purpose of the drift file is to provide ntpd with an approximate frequency correction (somewhere between -500 and +500) for use at startup. This "ballpark" correction is close enough to allow ntpd to quickly adjust the clock. > Or is it that ntpd has already set things up so that corrections as > per last value of drift file will continue indefinitely? When ntpd stops the clock continues slewing at the last rate and direction requested. > If it is the latter and if indeed my drift value is quite good (as > ntpd had run for many days already), it seems I can go for many more > days w/o ntpd and not get very much out of sync at all. ntpd continuously steers (i.e. slews) the clock to bring it as close as possible to the apparent correct time. These adjustments compensate for variations in clock behavior which are induced by factors such as system load and environmental conditions. -- Steve Kostecke <koste...@ntp.org> NTP Public Services Project - http://support.ntp.org/ _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
