Very Computer

by **Christopher Brown** » Sun, 04 Aug 2002 08:06:15

Quote:> Thank you for responding to my request for help. I took your
> suggestion(s). First, I checked the hardware clock and found it wrong.
> I changed it to July 24 and 15:36:00. I then booted up Linux only to
> find that the date was right but the time was 10:36:xx AM! I did a
> hwclock and got exactly that time again. I exited, rebooted and checked
> the hardware clock. The date and time were right! So, now what?

Next step: Install ntp, and sync your time against some nearby
servers. It'll sync up any time you're connected, and should be quite
helpful.
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by **Michael Lee Yoh** » Sun, 04 Aug 2002 10:16:43

Quote:> Next step: Install ntp, and sync your time against some nearby servers.
> It'll sync up any time you're connected, and should be quite helpful.

Here's a script that I run as a nightly root cron job just to make sure
the clock always stays where it needs to - quick and easy.

#!/bin/bash

TIMESERVER=time-A.timefreq.bldrdoc.gov
/usr/bin/rdate -s $TIMESERVER || {
echo "could not run /usr/bin/rdate -s $TIMESERVER" >&2 ; exit 1

Quote:}

/sbin/clock -w || {
echo "could not run clock -w" >&2 ; exit 1

Quote:}

exit 0

--

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-> - Larry Wall

by **oh_h..** » Sun, 04 Aug 2002 16:59:06

Note: followups to c.o.l.networking (since this is a networking-related
issue).

In comp.os.linux.networking Michael Lee Yohe

> Here's a script that I run as a nightly root cron job just to make sure
> the clock always stays where it needs to - quick and easy.

I think that running ntpd is better, since every few moments re-syncs
the time (and also keeps a drift file, which rdate does not (IIRC)).

However, if time is wildly out of sync then running ntpdate prior to
starting ntpd is prudent.

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by **Michael Lee Yoh** » Sun, 04 Aug 2002 18:12:17

Quote:> I think that running ntpd is better, since every few moments re-syncs
> the time (and also keeps a drift file, which rdate does not (IIRC)).

I have found that my system generally loses about 3 seconds per week.
Re-syncing the time every few moments is a waste of bandwidth on this
system. The solution I posted was merely one that was "quick and easy".

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by **oh_h..** » Mon, 05 Aug 2002 01:14:23

Quote:> I have found that my system generally loses about 3 seconds per week.
> Re-syncing the time every few moments is a waste of bandwidth on this
> system. The solution I posted was merely one that was "quick and easy".

I still think that, at least in Debian, ntpd is still quicker and
easier:

apt-get install ntp
(answer 'y')
(enter space-delimited list of ntp servers)
done.

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by **Eric P. McC** » Mon, 05 Aug 2002 05:10:10

Quote:> > I think that running ntpd is better, since every few moments re-syncs
> > the time (and also keeps a drift file, which rdate does not (IIRC)).
> I have found that my system generally loses about 3 seconds per week.

Consistent time loss or gain like that is extremely common.

Quote:> Re-syncing the time every few moments is a waste of bandwidth on this
> system. The solution I posted was merely one that was "quick and easy".

ntpd is not a stupid program. It attempts to determine your system
clock's drift rate - how fast and in what direction away from the
actual time it is moving - and provides that information to the
kernel. The kernel can then use it to keep the clock more accurate,
instead of just blindly updating it every few days.

Oh, and according to iptables, I waste about 26KB of bandwidth per day
keeping my small LAN's clocked synched. That's trivial even if you're
on 56k (although you obviously don't want it dialing every time ntpd
thinks your clock is wrong).

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Very Computer

System Clock keeps showing the wrong time/date

System Clock keeps showing the wrong time/date

System Clock keeps showing the wrong time/date

System Clock keeps showing the wrong time/date

System Clock keeps showing the wrong time/date

System Clock keeps showing the wrong time/date

System Clock keeps showing the wrong time/date