= NTP =

== Fixes if synchronisation fails following frequent suspend to RAM ==

On one of my machines, ntp had lost synchronisation. 
This appears to be related to frequent suspend to RAM, sometimes for a few days. In early versions of pm-utils (which is what I use for s2ram) there was a script to fix up ntpd - but that was removed long ago, in the belief that the clock would only drift for a maximum of 64 seconds realtime (not drift *by* 64 seconds!) and then ntpd would start to sync it. For systemd the preferred methods are apparently different. Anyway,I've now added the following script as  /usr/lib/pm-utils/sleep.d/48ntpd (mode 755) and things seem to work - using 'ntpq -p' I can sometimes see offsets of several hundred milliseconds (and increasing!) even when the box has sync'd to my local server, but it seems to stay accurate to within a second, and eventually syncs to a few milliseconds.


{{{
#!/bin/sh
# stop ntpd on suspend, fix and start fresh on wakeup

. "${PM_FUNCTIONS}"

case $1 in
    suspend)
        /etc/rc.d/init.d/ntpd stop
        ;;
    resume)
        /usr/sbin/ntpd -gq
        /etc/rc.d/init.d/ntpd start
    *) exit 0 ;;
esac
exit 0
}}}


== When the clock is too far away from the correct time ==

If ntpd bails out because the clock is too far from the correct time, try stopping ntpd, then use
{{{
ntpd -gq
}}}
to let it sync, and then restart ntpd. According to the man page, -g can be used multiple times if the clock is far adrift.