[ntp:questions] question regarding NTP configuration for clusters, and "cluster time" stability

rotordyn@yahoo.com rotordyn1 at gmail.com
Tue Oct 6 18:04:33 UTC 2009


On Oct 6, 11:52 am, Terje Mathisen <Terje.Mathi... at tmsw.no> wrote:

> Having an external server fail but still reply (a "falseticker") is an
> expected issue, it is solved by having at least 4 servers.

Right. But even if we require 4, there is the unlikely but possible
scenario of 3 going offline during the same period that the last one
is ill-behaved.

> (BTW, a single clock which jumps 5 minutes will be voted out in any
> redundant setup. It is only if you have just one or two servers, and one
> of these start drifting off slowly (at less than the 500ppm rate) that
> your internal machines would be willing to follow it without logging a
> time jump.)
>
> In your case I would setup at least one internal GPS-based server, and
> then fill out the config with several external servers. This way all
> your internal servers will still agree even if one of your reference
> sourced turn into a falseticker.

It's been suggested earlier in the thread, and would really simplify
the problem, but adding hardware is not at all possible.

thanks,
tim




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