[time-nuts] more of a time distribution question

John Hawkinson jhawk at MIT.EDU
Thu Mar 30 23:12:02 EDT 2017

Hal Murray <hmurray at megapathdsl.net> wrote on Thu, 30 Mar 2017
at 13:43:34 -0700 in <20170330204334.18A8D406063 at ip-64-139-1-69.sjc.megapath.net>:

> That should work too.  I don't know much about the Mac environment.  If it's 
> running a normal-enough ntpd it is already a server and you don't have to do 
> anything.  If not, you will have to build/install your own and/or poke holes 
> in the firewall rules.

It is worth noting that the ntpd that Apple ships is kind of bizarre,
and it does not actually adjust the clock on the Mac. (Instead it
writes to the drift file -- or at least it is supposed to -- and an
Apple process called "pacemaker(8)" readthe drift file and tries to
maintain the systme clock. In my experience (only through Yosemite --
10.10) this mechanism was horribly broken and did not maintain my
laptop's system clock in any useful way.)

This probably doesn't actually affect the intended use (as the goal is
to keep machines in sync, not to keep them accurate), but anyone who
messes with ntpd under OS X should be aware that it is "weird."

Building the stock ntpd under OS X works just fine, and I recommend that
for anyone who wants to tinker with ntp under OS X.

--jhawk at mit.edu
  John Hawkinson

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