Hello Serge, You're right! I missed the -b option in ntpdate.
> That's very doable, but requires some amounts of efforts. ;-) I understand that. The system is a "transportable" system. It is used to mesure some transmission time over a network (packets contain utc timestamp themselves). It can be moved to different sites in the network. I would like to avoid the user of the system to wait for "one day" before he gets realiable results. The system is a "blackbox", which is suppose to work "out of the box". Also, in this context, "setting up a DCF77 or GPS refclock" is not always possible (we actually do support NTP + GPS refclock). Maybe I should look for a pci board that is able to keep good time - even with offset but limited drift- with no external time source... If anyone has ever heard of this... Thanks for your answers Serge, Regards, Thierry MARTIN Serge Bets a écrit : > Hello Thierry, > > On Tuesday, February 19, 2008 at 16:43:10 +0100, Thierry MARTIN wrote: > >> # rm /etc/adjtime; >> # ntpdate ntp.cines.fr; >> # hwclock --systohc; > > This procedure sets the RTC once, but does not evaluate its drift. While > adjtimex --adjust needs to know the runtime drift rate of the RTC. So > this should be: > > | # ntpdate -b ntp.cines.fr > | # hwclock --systohc > | wait some hours (minimum 1 to 24 hours depending on hwclock > | version) while the machine continues to run its usual tasks > | # ntpdate -b ntp.cines.fr > | # hwclock --systohc > > This last command sets the RTC again *and* writes into /etc/adjtime > the needed drift correction factor in seconds per day. Now only can > adjtimex --adjust work correctly. Works, but is still not the best > method to set the kernel freq, if you don't mind me to repeat. And after > all that is finished, don't forget to set /etc/adjtime to a sane > power-off RTC drift rate (see my next article). > > Note that the nude ntpdate without option does not set the system clock > immediatly nor correctly. For this procedure -b (force step) is > required. Or something better. > > >> Keeping a linux system with the correct time without any external >> synchronisation really seems hard... > > That's very doable, but requires some amounts of efforts. ;-) > In comparision, setting up a DCF77 or GPS refclock for the ntpd daemon > is not so deadly complicated. > > > Cordialement, Serge. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
