[ntp:questions] Re: ntp client over satellite and no CMOS battery

Bob Beers bob.beers at gmail.com
Tue Oct 4 20:18:44 UTC 2005

Hello again all,

While it was an interesting excursion, I wonder if I could bring
this thread back around to the original topic?

There have been a few other threads recently which touch a bit on
the same subject matter and I have learned a bit from them.

sync immediately
ntpd for dummies
ntpd and hwclock

I still have not completely solved my original problem,
which I will restate now:

A linux unit (basically an ntpd client) without a hwclock battery
lives on the remote side of a satellite connection. Every time
it comes alive from power cycle, the hwclock sets the system clock
to 2000-Jan-01.

Under ideal circumstances, the network is available before the client
starts ntpd -g -N, and all is well; the system clock is set to
current time very quickly. I have a 3 line ntp.conf on the client:

server <> iburst
driftfile /etc/ntp.drift
logfile /var/log/ntp.log

( where <> is my linux ntpd server on the
internet side
of the satellite using four pool.ntp.org <http://pool.ntp.org> servers, and
to only serve time to my clients )

However, sometimes, the network link does not become available until
after ntpd has been started. If the initial iburst to the server
doesn't get any reponse, and then the network does become available,
it takes several minutes vs. a few seconds to get the clock set.

Q1: Can I modify that behavior?

If not, I have in mind to run a cronjob which tests network connectivity
to the ntpd server and (re)starts ntpd, to get the quick clock adjust once
the network is available. I would still need to detect when the state
was "good", and then could set my hwclock manually (optional) and cancel
the cronjob.

Better ideas most welcomed.

This is important (to me) because I have an app to run on the client
which uses timestamps, and I want to delay starting the app until after
the system clock is set, but, of course, as quickly as possible. And
I don't want to delay the rest of the boot process, just the one app.



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