Joachim Schrod wrote:
Richard B. Gilbert wrote:
If you want to use four peered servers you need a minimum of seven
upstream servers to do it right; one unique server for each of your
servers and three others to be shared by all. Do you REALLY need four
peered servers?
<snip>
Perhaps I should make more explicit why I'm posing this questions,
obviously I
haven't been clear enough. My main interest is to collect information,
to be
able to write up a procedural step-wise how-to in the NTP Wiki,
respectively
improve the page that is there. (Or I will place it somewhere else if
the Wiki
won't take it). I am not interested in something unique or clever, I'm
interested in best practice for generic medium companies. With as few
decisions
and as little work as possible. Something like: You want NTP? Do a, b,
c; then
you're finished.
It's not quite that simple!
First, you need to define your requirements:
a. accuracy
b. reliability
c. traceability
d. security
Then you need to consider your resources.
a. how much money can you spend on it.
b. how much time can you spend.
c. available hardware
d. available expertise
e. available upstream servers
From your description, your friend is without experience, and could
tolerate errors of one or two seconds. His needs for reliability,
security and traceability are not defined. The availability of upstream
servers is limited. What are the consequences of his time being off by
four seconds? What are the consequences if different systems have times
differing by X milliseconds.
When you have defined the requirements, you can attempt to design a
system that meets those requirements.
I would suggest that your friend configure a single server with four
upstream servers and configure all his clients to get time from that
server. If that single server fails, the client's clocks will start to
drift, perhaps by as much as four seconds per day but probably less than
that. In twenty-four hours, two different systems might differ by as
much as eight seconds but again, probably less than that. If he can
detect and repair the failure within twenty-four hours, will this meet
his requirements? This is low cost, easy to do. If experience
demonstrates that it is less than ideal, he can improve it.
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