Time server...how to set it up on FC1?

[Rodolfo J. Paiz]

At 14:19 4/12/2004, you wrote:
>Yes and no ntpd is full time and ntpdate only runs until the time is
>set. They're in essence the same daemon and when ntpdate starts it sees
>ntpd and shuts itself down.

Not quite true. "ntpdate" checks the time on an NTP server just once, and 
then forcefully changes the local system time to whatever result it got 
from the server, regardless of what that result was and with no sanity 
checks. If the server is 10 years off from the local system time, the local 
system time *still* gets smacked instantly to match the server. It just 
happens to use the NTP protocol to communicate with an NTP server.

"ntpd", on the other hand, checks two or more servers initially every 64 
seconds. After several (8 or more, usually) queries, when it feels that it 
has a sufficiently solid idea of what the "correct" time is Out There, it 
begins slowly sliding the local system clock to match that "correct" time 
without making any sudden moves that might confuse local applications 
and/or server processes.

Also, ntpd provides very high precision, and it will not adjust the system 
clock (it will exit and report an error instead) if the local time if off 
by more than 120 seconds. Given that my server clocks are usually less than 
0.01 seconds away from the "correct" time and that theoretically ntpd is 
capable of maintaining an error of less than 0.0000001 seconds, you can see 
that it considers *two minutes* as an ungodly, horrendous, utterly 
unacceptable misconfiguration.

If at all possible, one should avoid using ntpdate at all. Simply run ntpd 
on one box, set all others to adjust their time to that server (which also 
uses NTP), and be done with it. After the initial half-hour (approximately) 
startup period, it all "just works" beautifully.

Cheers,


-- 
Rodolfo J. Paiz
rpaiz at simpaticus.com
http://www.simpaticus.com