On 17/03/16 20:26, Alan McKinnon wrote: > On 17/03/2016 08:50, Håkon Alstadheim wrote: >> I have a server SUPPOSED to be running 24/7, but every once in a while >> during a prolonged absence the box will go down. The Real Time Clock >> will drift, and in the rush to get the box up again I let everything >> boot up automatically and get both wrong time on the main systems, and >> different times on the various systems. >> >> My setup has a main server which does NTP, but with no direct link to >> the outside. Router&firewall /have/ to be booted booted later (dumb >> setup, don't ask), after which I can finally get correct time from NTP. >> >> NTP initiates "11 minute mode", which makes /etc/adjtime useless as far >> as I understand. Anybody have a /correct/ way to account for RTC drift >> on a box running ntpd? Right now I have a ---file in >> /etc/cron.d/time-bad like so: >> * * * * * root adjtimex -S 5 >/dev/null 2>&1 </dev/null >> --- >> >> Combined with an old-fashioned setup for hwclock during boot and >> shutdown. This feels really wrong, and I have no idea what I am doing. >> >> TLDR: Anybody have a /correct/ way to account for RTC drift on a box >> running ntpd? >> >> > > > When the box was off, all questions of accurate ntp tracking are moot. > ntp is designed around the idea that every second happens but from your > machine's point of view they didn't happen since it was powered down. > > I would go the really simple route and force ntpdate to run once during > boot up before ntpd is started, thereby avoiding the entire issue. > Sometimes correctness really doesn't matter, this looks like one of those. > > > alan >
add a cheap gps setup as the reference clock to the server, or even better is a dedicated time server (either a real one or a raspberry pi/gps) on the network if you have internal connectivity. Going super cheap, but not quite as accurate for me was an arduino and rtc on a bluetooth pan for when the network was down but I needed a reference (to power up the real server :). google "arduino time server" for plenty of options :) BillK
