diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc index 8e54ddc..be39a27 100644 --- a/doc/chrony.conf.adoc +++ b/doc/chrony.conf.adoc @@ -771,9 +771,10 @@ driftfile @CHRONYVARDIR@/drift [[fallbackdrift]]*fallbackdrift* _min-interval_ _max-interval_:: Fallback drifts are long-term averages of the system clock drift calculated -over exponentially increasing intervals. They are used when the clock is no -longer synchronised to avoid quickly drifting away from true time if there was -a short-term deviation in the drift before the synchronisation was lost. +over exponentially increasing intervals. They are used to avoid quickly +drifting away from true time when the clock was not updated for a longer period +of time and there was a short-term deviation in the drift before the updates +stopped. + The directive specifies the minimum and maximum interval since the last clock update to switch between fallback drifts. They are defined as a power of 2 (in @@ -785,8 +786,10 @@ fallbackdrift 16 19 + In this example, the minimum interval is 16 (18 hours) and the maximum interval is 19 (6 days). The system clock frequency will be set to the first fallback 18 -hours after last clock update, to the second after 36 hours, etc. This might be -a good setting to cover daily and weekly temperature fluctuations. +hours after last clock update, to the second after 36 hours, and so on. This +might be a good setting to cover frequency changes due to daily and weekly +temperature fluctuations. When the frequency is set to a fallback, the state of +the clock will change to '`Not synchronised`'. + By default (or if the specified maximum or minimum is 0), no fallbacks are used and the clock frequency changes only with new measurements from NTP sources,