> Le 09/11/2015 20:12, Rainer Weikusat a écrit :
> >After booting, the discrepancy between the RTC clock and the actual time
> >is unknown.
>     I remember having had a problem with two servers when the time
> discrepency reached 5mn (It was for kerberos authentication). We
> discovered that one of the two was not synchronized by NTP at all.
> The problem showed up after 4 years with many reboots and no clock
> adjustment on the non-synchronized host.

>     NTP does not adjust the RTC brutally; it seems to adjust slowly
> the frequency so that synchronization happens without the process
> being noticeable to other apps - it can take hours. On shutdown it
> saves the RTC settings in /var/lib/ntp/ntp.drift, and (AFAIU)
> /var/lib/hwclock/adjtime. After some days of running NTP, your RTC
> is well trimmed and does not drift much. It does not stop running
> when you power-off your computer. Therefore, at startup the
> discrepancy is very small - unless the battery of the RTC is dead or
> you stopped the computer for a year.

>     Everything above is non-authoritative; it is the result of my
> own observations.