[SunHELP] time sync; slew

[Jim Pennino]

On Thu, Jan 16, 2003 at 11:49:05AM -0500, Markham, Richard wrote:
> I wanted to confirm this.  It seems ntpdate, xntpd, and ntp are all
> pointing to the same concept.  From what you tell me that if were to
> manualy start the xntpd dameon that it would hard change the time,
> then slightly adjust it there afterward.  I would definitely want
> the hard change to occur on bootup as opposed to while the system
> is in use. So I'll place a tested configuration in place and 
> schedule a reboot.

You really need to go to www.ntp.org and do some reading.

Ntp is the protocol, ntpdate is a command that will set the system time
from ntp servers, and xntpd is a deamon that uses ntp to keep the
clock accurate to small (usually 10s of microseconds) fractions of a
second.

Look at the /etc/init.d/xntpd script. It is ntpdate that "slews" the
time to get it close before xntpd is started.

If the time is already close, ntpdate just makes it closer.

If you want to bring a running system close to the real time without
an abrupt change, call ntpdate manually with the -B option. This can
take hours depending on how far off you clock is, but in some cases
beats doing a reboot.

That is, setup the ntp.conf file, touch ntp.drift so it exists, as
root do:

ntpdate -B ntp-server-name-1 ntp-server-name-2

When ntpdate finishes, your clock will be within a fraction of a second.

Do:

/etc/init.d/xntpd start

After a while do:

ntpq -p

to see how things are running.

For details, man ntpdate.


-----
Jim Pennino