Re: NTP weirdness

On Mon, Oct 16, 2006 at 08:02:12PM -0300, Henrique de Moraes Holschuh wrote:
On Mon, 16 Oct 2006, Roberto C. Sanchez wrote:
I have two machines which are running NTP. They both synchronize to
these servers in /etc/ntp.conf:

server ntp2.usno.navy.mil
server ntp-1.vt.edu
server ntp-2.vt.edu

Now, here is where the weidrness comes in. The two servers' clocks are
perfectly in sync. I have three machines (2 desktops/1 laptop) which
synchronize to the two above named servers (not the upstream NTP
servers). Anyhow, two of them are always within five seconds of the two
local NTP servers. The third machine gains about 5 minutes every two

Any NTP drift above half a second means something is completely broken, so
*none* of your client machines are working fine. The two servers seem to
work right. Make sure to also configure the two servers to *peer* each
other, btw.

vague memories in my head that ntp won't sync more than a half second
or so at a time, you have to use something else to get them closer and
then ntp can do it. I've used ntpdate in the past as a one-time sync
and then its worked after that. Also had a machine that was drifter
faster than ntp could keep up with, but after a few days of hitting
ntpdate randomly, it was able to calculate the drift enough to keep up
after that point. this is all vague memory, ymmv widely.

A

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