[ntp:questions] Re: Drift handling....

Roman Mäder newsXXF.10.rmaeder at spamgourmet.com
Thu Jan 5 08:42:17 UTC 2006

> Next, the ntpd-server should have some strategy to handle with the
> situation. A few suggestions:
> a) recalculate the 'actual' drift against other servers, and reconsider
> the server selection in case other servers result in a 'sane' drift
> value, or use a 'weighted average offset', weighting the 'good' servers
> more than the others;
> b) recalculate the drift over a longer period (until it is within, or
> limited by the 'normal range') and use that one (1s additional offset in
> a 20s period results in a much larger calculated drift then 1s
> additional offset over the past few hours or day);
> c) don't adjust your drift at all, but assume that a 'glitch' caused the
> additional offset; correct for the additional offset, and continue with
> the same drift value (or adjust it a very little bit);

if an inexplicable (to ntpd) glitch happens, make as few assumptions as
possible. Probably the mode that ntpd uses when it starts without a drift
file is useful here. Something like:
- correct any offset
- get a quick estimate of the drift
- resume normal operation


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