[ntp:questions] suggestion

gizero gizero at gmail.com
Mon Oct 26 15:59:13 UTC 2009


Hi group users,

I'm writing this, since I am extremely confused about how to configure
network time sync for an embedded system I'm working on.

Possible time sources for the box are:
1. onboard RTC (used at boot to start-up system clock)
2. NTP server (optional and configurable: used as soon as reachable
for synchronisation)
3. local GPS connected to serial line (an alternative to NTP: used as
soon as it fix ad send timestamps)

When first thinking about the time sync problem, I was pleased to
learn that ntpd was able to handle the time data from the GPS as a
special time source, together with gpsd daemon. So I thought of using
it instead of any sort of cronjob calling ntpdate to step the clock.

Then I learned - not so deeply, I have to say - that ntpd was a lot
more than I expected in term of algorithms guessing the best source
among many.

My question is: should I expect to be able to set-up my configuration
that allow a single NTP server to be defined and, optionally, the GPS,
when available? Or am I out of the track?

I'm reading many documents, but they all refer to configurations with
a pool of servers available. The only NTP server, if available, is
considered precise enough for the application. Maybe only in future
scenarios more than one could be available, not now.

Thanks in advance for any kind help or, maybe, pointer to more related
documents than I found
Regards,
Andrea




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