---------- Forwarded Message ----------
Subject: Re: [Cooker] NTP Installation
Date: Mon, 3 Sep 2001 10:17:03 -0600
From: David Eastcott <[EMAIL PROTECTED]>
To: Pixel <[EMAIL PROTECTED]>
Cc: Cooker <[EMAIL PROTECTED]>
On September 3, 2001 04:06 am, you wrote:
> David Eastcott <[EMAIL PROTECTED]> writes:
>
> [...]
>
> > I am wondering why the installer does not also create the
> > /etc/ntp/step-tickers file and place the entered time server into it as
> > well?
> >
> > I noticed that the clock on the computer was out by a large amount (used
> > ntpq -pn to get statistics). Consequently, it was taking a very long
> > time to bring the computer's time into sync with the time server.
> >
> > I checked the ntpd init script and it would use the contents of the
> > step-tickers file to correct the computer's clock immediately before
> > running the ntp daemon.
>
> any idea why it doesn't use the server line in /etc/ntp.conf?
According to the material at www.ntp.org, they recommend that you have at
least 5 servers specified in the ntp.conf file. So the question becomes
which one does it use. The ntp developers elected to have the user sync the
local clock first from a reliable source (that's the reason for the
step-tickers file), then run the daemon to keep it sync'ed.
>From my limited understanding the reason for at least 5 servers has to do
with a couple things: multiple sources in case one or more become
unavailable and, the ntp daemon mathematically combines the values from each
of the servers to form a "better" time. Another issue is if the clock error
is too large (difference between the workstation and the time server), the
NTP daemon will not be able to slew the computers clock or it will take a
very long time to achieve synchronization.
In the case of a work station or internal servers, a single internal time
server is OK (as drakx currently sets it up), two would be better (in case
one is down). This is the way I have set most of my equipment up;
workstations have 1 internal time server and internal servers have 2 in the
ntp.conf file, the step-tickers file contains the name of the server I want
the computer to sync to. My internal time server(s) has 5 external time
sources that are accessed via the internet (permenant connection), again I
have the step-stickers file set to the external server most likely to be
available to get the initial time sync.
Final note (not really but I am going to stop anyways), systems which have
permenant or long term connection to the internet will obtain the most
benefit from NTP.
Those which use dial up services most likely will not since the use of the
step-tickers files only occurs (normally) at boot up. Dial up users will
need the ntpd "restarted" once the connection is made and the connection
needs to remain for a reasonable period so that ntpd can calculate a
reasonable value for the drift file. It may be that an alternate method is a
better choice for them..
dave
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