[Dovecot] ntp revisited (so what to do ?)

[Ed W]

On 10/05/2011 22:36, Stan Hoeppner wrote:
> On 5/10/2011 8:50 AM, Ed W wrote:
> 
>> So, in practice it's fairly irrelevant to be hooked to a stratum 1 for
>> most purposes and if you really want to get obsessed about accurate time
>> (I'm going through this obsession phase right now...) then just get a
>> local GPS attached to your machine...
> 
> NTP is free and the accuracy, when properly configured, is better than
> that required by any network application.  If your goal is sub
> millisecond accuracy, it's not due to any actual network application
> requirement.

I'm not sure if I understand your point?

My point was that some Stratum 1 servers are less than 1ms accurate.
You were making excited noises about being given access to a Stratum 1
server via an internet connection and I was simply pointing out that
such a setup does not necessarily give super accurate time at your side
(especially compared with adding a $50 GPS to a local machine - which of
course makes that machine a stratum 1)

Also, I don't understand your point about NTP being free?  Chrony is GPL?

Finally you say that NTP is "better than required", but in fact NTP can
often take quite a long time to converge to fairly accurate time? If the
machine is rebooted (less common for a server, but more common for
desktop machines), and the RTC is inaccurate, then it can take quite a
long time each boot before the clock is decent.  One citation here:
	http://lists.ntp.org/pipermail/questions/2011-April/029223.html

Chrony converges much more rapidly in general

NTP is clearly "good enough", I was just trying to bring other ideas to
the attention of the OP (and now you).  Chrony is a very good solution
and solves a number of problems with timekeeping that perhaps you were
not even aware that you had?

Kind regards

Ed W