Re: [PLUG] ntp

The reason for this behavior, if I remember correctly, is to avoid breaking certain applications which do not gracefully handle sudden changes to the system clock.

About 2 years ago I worked, briefly, with some systems using ntp. Turns out if the time is off by some small amount (less than a minute IIRC), it simply stops changing the target system's time because it "thinks" something is drastically wrong.

Seems like a cron job to re-sync is a good idea to me.

Eric

On Wed, Jul 8, 2015 at 2:24 PM, Keith C. Perry <kperry@daotechnologies.com> wrote:

I hope you're saying that in jest Walt. In my experience ntpd slips way too much. Once clocks get out of sync by too much ntpd won't nudge it back and that can happens more often than not on interactive and poorly tuned HPC nodes.

You can have the same issue on system boots.

My apologies if I'm misinterpreting tone.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Keith C. Perry, MS E.E.
Owner, DAO Technologies LLC
(O) +1.215.525.4165 x2033
(M) +1.215.432.5167
www.daotechnologies.com

----- Original Message -----
From: "Walt Mankowski" <waltman@pobox.com>
To: plug@lists.phillylinux.org
Sent: Wednesday, July 8, 2015 2:15:39 PM
Subject: Re: [PLUG] ntp

But...but...

You do realize that's essentially what ntpd does, only ntpd does it
way better, right?

Right?

On Wed, Jul 08, 2015 at 01:37:59PM -0400, Keith C. Perry wrote:
> That's what I do. Run "ntpdate us.pool.ntp.org" every 4 to 6 hours on critical / core systems.
>
>
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> Keith C. Perry, MS E.E.
> Owner, DAO Technologies LLC
> (O) +1.215.525.4165 x2033
> (M) +1.215.432.5167
> www.daotechnologies.com
>
>
> From: "Bill East" <wm.east@gmail.com>
> To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
> Sent: Wednesday, July 8, 2015 1:35:29 PM
> Subject: Re: [PLUG] ntp
>
>
>
> I just had to deal with a vendor installation which was about 4 seconds off the ntp server it was supposed to be synced with. Come to find out the vendor ran a ntpdate command once a day and the vm was drifting 4 seconds in the 24 hours between. Their solution was to run the command once an hour instead.
> On Jul 8, 2015 1:13 PM, "Eric Riese" < eric.riese@gmail.com > wrote:
>
>
>
> So I just noticed that my KVM server's clocks were way off. The host OS was 4 minutes behind time.gov and the guests were 4 minutes ahead of time.gov .
>
> Turns out the host did not have ntp installed at all. It's Ubuntu 12.04 and was installed as some sort of minimal installation. A sudo apt-get install ntp and five minutes later it's in good shape.
>
> The guests are debian installs from turnkeylinux.org and they have ntp installed but were not running by default!
>
> To think, Google runs it's own internal NTP servers and had to spread the leap second out over a day, and I'm off by whole minutes!
>
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___________________________________________________________________________
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Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug

___________________________________________________________________________
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Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug