[PLUG] NTP

Wil Cooley wcooley at nakedape.cc
Thu Nov 20 17:55:54 UTC 2008


On Thu, 2008-11-20 at 10:45 -0700, Carlos Konstanski wrote:

> - You cannot run ntpdate while ntpd is running.  You must stop ntpd,
>    run ntpdate, and start ntpd.

Not entirely true; you just have to use the '-u' option w/ntpdate.

> - ntpd will not set the clock if it too far askew.  It is imperative
>    to use ntpdate to get the clock set correctly before starting ntpd.
>    Gentoo handles this by having two init scripts - one to run ntpdate,
>    and another to start ntpd.  You could easily create your own ntpdate
>    initscript, and schedule it to run before ntpd (but after the
>    network is up).

Also not entirely true. The -g option to ntpd will allow it to set the
clock without skew limitations, but only once.

For some reason, the ntp.org ntpd developers want to retire the ntpdate
program, so the current recommendation is to run ntpd in one-shot mode:
'ntpd -gq'.

> - You should make sure your hardware clock is correct by ensuring that
>    the motherboard battery isn't dead, and by using hwclock to set it
>    (once you have used ntpdate to set the software clock correctly, of
>    course).  Then when you boot your box you might stand some chance of
>    getting a reasonably accurate time, one that is close enough for
>    ntpd to use.

Wil
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