Re: NTP dynamic servers?
On Tue, 23 Jan 2007, Jacques Normand wrote:
> you stay offline for a long time. I also do not know what happen at
> startup to correct for the skew of the rtc during the shutdown. If it is
> taken care of by ntpd at start, then you have one less reason to leave
> it on...
ntp can do two things. It can "step" time, which is dangerous if it makes
the clock go backwards in an already running system (i.e. not during early
startup), or it can slew time (make the clock slow down a bit or go a bit
faster) until the time is correct.
If the difference is too big, slewing is not possible, as slewing cannot
make the clock run that much faster or that much slower than real time
for obvious reasons.
If ntp is slewing time, you better don't kill it until it is done.
Anyway, if the machine is not going to be connected to a network with
timeservers most of the time, install the "chrony" package instead of ntp.
"chrony" is designed for this kind of situation, where the machine stays a
lot of time offline. It will keep time correct better than NTP in such a
situation, and it will be easier on the time servers too.
ntp really *is* for machines that are constantly in contact with either
other ntp servers, or directly connected to a reference clock (GPS, atomic
clock, etc). For all other uses, you have "chrony".
As for ntpdate, it is something you should just use when the system is in
single user mode or during early startup.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
Reply to: