[ntp:questions] Default total number of servers NTP wants to have when using pool .....

Harlan Stenn stenn at ntp.org
Thu Dec 18 00:21:05 UTC 2014

Miroslav Lichvar writes:
> On Wed, Dec 17, 2014 at 12:04:04PM +0000, Harlan Stenn wrote:
> > I'd love to see discussion about "what should the default number of
> > servers queried be for the 'pool' directive?"
> The "How do I use pool.ntp.org?" page [1] is pretty clear, quoting:
>   Be friendly. Many servers are provided by volunteers, and almost
>   all time servers are really file or mail or webservers which just
>   happen to also run ntp. So don't use more than four time servers
>   in your configuration, and don't play tricks with burst or
>   minpoll - all you will gain is extra load on the volunteer time
>   servers.
> > There is clearly a tradeoff, and I'm inclined to say that "between 5 and
> > 9" is probably a good number.
> Ok, but examples of ntpd configuration using pool.ntp.org should follow
> their policy. Maybe you can convince them to change it. Do you think
> the servers are ready to handle twice as many clients?
> [1] http://www.pool.ntp.org/en/use.html

What works best for a running instance of ntpd is not always going to be
what works best for the pool servers.

Choosing the right balance is something that happens "now" and the
balance point will change over time.

The ntp.conf generator project NTF wants to work on can help with that.
As soon as NTF gets the resources to move forward with that, it will happen.

With decent GPS pucks costing <US$40, how difficult would it be for
people to choose to buy one of those for their own use?  Obviously the
answer is "that's too much money and trouble for me."  So they could
send "less than $40" to:

- NTF and NTF can work on providing some pool servers

- their ISP and have their ISP provide NTP servers

I'm sure folks can think of other ideas, too.

Note that if Somebody is going to provide a pool server, that might mean
they also have to get some sort of small machine to plug the GPS into.
The total cost for that might still be under $US100, and there would
likely be ongoing maintenance and operational costs.

Seems to me there is a lot of cost-shifting going on here.


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