Time Synchronizing Between Two Servers

Chuck Swiger cswiger at mac.com
Thu May 3 15:07:41 UTC 2007


illoai at gmail.com wrote:
[ ... ]
> It may very well be noisier than just serving out ntp
> to the local network, what with talk about elections
> and such every 4 minutes, but generally everything
> is kept within 0.050 seconds (and running ntpd on
> all of the local machines feels like serious overkill).

Simply setting the date upon system boot and maybe once a day using cron to 
call ntpdate or whatever is probably good enough for any client machine, and 
OK for non-important servers where the exact timekeeping doesn't matter much.

ntpd is tiny by modern standards-- it's much smaller than a single Perl or 
Apache httpd+mod_Perl/PHP/whatever child process.  :-)  Normally, you choose 
your three (or more) most important servers, and run NTPd on them in a 
peer-aware ring with some external servers from the NTP pool, and then call 
ntpdate or run ntpd against only your local NTP resources for the rest of your 
machines.

Sun SPARC machines have good HW clocks, and also some of the newer Macs also 
seem to have consistently low values in ntp.drift and handle timekeeping well.

-- 
-Chuck



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