Re: ntp and hwclock
On 2007-01-20, Douglas Allan Tutty wrote:
> I'm running Etch amd64 ntp on my home system over dialup ppp.
>
> I stopped using chrony because I was having some problems and it
> couldn't talk to my rtc anyway.
>
> Our power can be unreliable and I don't have a UPS. Since ntp doesn't
> adjust the hwclock, right now the only time it gets updated is at
> shutdown.
>
> What would be the disadvantage of having a cron.hourly script run
> /etc/init.d/hwclock.sh stop ?
This script is unrelated to ntp (or any other time-sync service).
Linux kernel updates CMOS (hardware clock) time every 11 minutes.
In-kernel clock, that uses various CPU/Chipset hardware and is stable
enough. Its precision is as good as CPU frequency high (mostly). Any big
drift may be caused by bugs in the kernel, low precision of CMOS while
computer is powered off.
For a vary good precision of local time, time-syncing services are
used. But in fact, to have vary precise time, one must run computer
for a very long time with very good Internet connection to many time
servers.
--
-o--=O`C Denis
#oo'L O 1981-2006
<___=E M
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