Re: [gentoo-user] Server system date synchronizaion

[Alan McKinnon <alan.mckinnon@gmail.com>]

On 26/04/2013 20:36, Stroller wrote:
> 
> On 26 April 2013, at 16:41, Alan McKinnon wrote:
>> ...
>> So here's what you do: sync everything to your ISP's time servers.
>> Chances are good they do a better job than you can, just like with DNS
>> caching.
> 
> 
> I'm not sure if my ISP offers time servers, but Apple and MS both run time servers which are publicly accessible (presumably from any o/s).
> 
> I've never changed my laptop from its default, to sync with time.euro.apple.com, but my Linux boxes all use the public ntp pool, so I was surprised to read the other comments claiming the latter to be inaccurate.
> 
> Whenever I restart /etc/init.d/ntpd on my Linux boxes I can see their time match that of my laptop, as consistent as I can see, i.e. less than a second's difference between them.


ntpd has some wicked amazing optimizations built in, much more so if you
use multiple upstream sources. If one of them drifts, the software is
able to recognize it and defer instead to other sources that seem more
stable. It's like magic, the dodgy data tends to fall out of the system
leaving just the good data. Which is exactly what you want when using
volunteer resources of unknown and variable quality.

I'd compare the public ntp pool to a privateer race team - they can be
awesome, do amazing things with limited resources and often win races.
But for consistency and the best of the best, you need the Honda and
Yamaha factory teams (complete with obscene budgets).

For laptop, desktop and even most company's server needs, the public ntp
pool is perfectly good enough, which is what I think you observe in your
environment.


-- 
Alan McKinnon
alan.mckinnon@gmail.com