Re: [OT] Achieving Time-Synch at mailserver

[Tim Goodwin]

> Personally, I've looked at the TAI library with interest but I've never
> seen a good reason to move away from xntpd for time synchronization.

If you want your system to tick TAI, clockspeed is the only game in
town.

>I find it convenient to have xntpd take care of
> handling changing system clock drift for me (and I have a few machines
> that don't have consistent clock drift),

I have some prototype code to handle this.  It's a bit kludgy, but it
seems to work well enough on 50+ machines here.

But in general you're right: xntpd is time synchronization for the
masses; clockspeed (as yet) is only for those who like playing with
their toys, or have serious religious objections to UTC.

Tim (who scores on both counts :-).

Re: [OT] Achieving Time-Synch at mailserver

[Russ Allbery]

Daniel Augusto Fernandes <[EMAIL PROTECTED]> writes:

> I've been using NTP for a long time with success! How does clockspeed
> compare to NTP? Is there any tai time server?

xntpd does two things (well, three, actually).  It contacts remote time
servers periodically to correct its notion of time, and it determines the
"natural drift" of your system clock and constantly corrects for it.  It
can also provide the time to remote machines that are querying it.

clockspeed separates these different functions.  You first take a few
measurements to establish your clock drift, and then you run a daemon that
just adjusts for that known drift and doesn't continue to poll other time
servers and adjust.  You can periodically take another measurement and see
if the drift has changed.

Personally, I've looked at the TAI library with interest but I've never
seen a good reason to move away from xntpd for time synchronization.  It
works fairly well, I find it convenient to have xntpd take care of
handling changing system clock drift for me (and I have a few machines
that don't have consistent clock drift), and I like being able to use any
convenient server as a server for ntpdate in a pinch.  I understand the
xntpd stratum setup and we have a fairly nice setup of multiple stratums
here.

The clockspeed approach has the advantage of working fine for a system
that's only rarely connected to the network, but to me a computer without
network connectivity is almost worthless except for playing games (for
which clock synchronization doesn't really matter).

-- 
Russ Allbery ([EMAIL PROTECTED]) 

Re: [OT] Achieving Time-Synch at mailserver

[Russ Allbery]

Peter van Dijk <[EMAIL PROTECTED]> writes:

> But when does xntpd send out requests then? It seems to only do so every
> once in a while, and if I'm not dialed in at that time, it fails.

Most of what clock synchronization software does, though, is to figure out
how much your clock drifts naturally and then just keep adjusting for that
drift.  It only needs occasional external data to correct it's idea of the
internal drift, not constant data.

-- 
Russ Allbery ([EMAIL PROTECTED]) 

Re: [OT] Achieving Time-Synch at mailserver

[Aaron L. Meehan]

Quoting martin langhoff ([EMAIL PROTECTED]):
>   The other machine has a intermittent connection, so I'm looking for a
> way to synchronize on a command (instead of a daemon). I checked CPAN
> for NTP and found nothing. The Net::Time module doesn't seem to help as
> it's looking for a time server, and not a NTP server. 

You might check for the commands "rdate" or "netdate" -- both will get
the time from another machine.  On our PC's with linux, we further
need to use the "clock" or "hwclock" commands to set the hardware
clock to match the system clock.  We run these out of a cron job every
so often, and only run ntpd on one computer in the network.

Aaron

Re: [OT] Achieving Time-Synch at mailserver

[Daniel Augusto Fernandes]

Chris Johnson wrote:
> 
> On Thu, Sep 21, 2000 at 11:39:32AM -0300, martin langhoff wrote:
> >   I have 2 mails servers that I want to synch (and keep with the world's
> > clock). As one is in co-location, there's no problem at all: I'm
> > installing NTPd (although I have some security concerns).
> >
> >   The other machine has a intermittent connection, so I'm looking for a
> > way to synchronize on a command (instead of a daemon). I checked CPAN
> > for NTP and found nothing. The Net::Time module doesn't seem to help as
> > it's looking for a time server, and not a NTP server.
> 
> Try Dan's clockspeed package: http://cr.yp.to/clockspeed.html
> 
> Like everything Dan writes, it's small, simple, safe, and works well. It's
> particularly well suited to keeping time on a computer with an intermittent
> network connection. I use it on all my boxes (even the well connected ones).
> 

I've been using NTP for a long time with success! How does clockspeed
compare to NTP? Is there any tai time server?


Daniel Augusto Fernandes (DAF tm)   [EMAIL PROTECTED]
GCSNethttp://www.gcsnet.com.br/

 Se você não encontra
 o sentido das coisas
 é porque este não
 se encontra, se cria.
   Antoine Saint-Exupéry

Re: [OT] Achieving Time-Synch at mailserver

[Chris Johnson]

On Thu, Sep 21, 2000 at 11:39:32AM -0300, martin langhoff wrote:
>   I have 2 mails servers that I want to synch (and keep with the world's
> clock). As one is in co-location, there's no problem at all: I'm
> installing NTPd (although I have some security concerns). 
> 
>   The other machine has a intermittent connection, so I'm looking for a
> way to synchronize on a command (instead of a daemon). I checked CPAN
> for NTP and found nothing. The Net::Time module doesn't seem to help as
> it's looking for a time server, and not a NTP server. 

Try Dan's clockspeed package: http://cr.yp.to/clockspeed.html

Like everything Dan writes, it's small, simple, safe, and works well. It's
particularly well suited to keeping time on a computer with an intermittent
network connection. I use it on all my boxes (even the well connected ones).

Chris

RE: [OT] Achieving Time-Synch at mailserver

[Ihnen, David]

> -Original Message-
> From: Peter van Dijk [mailto:[EMAIL PROTECTED]]
> > xntpd, even on dial-up machines.
> 
> But when does xntpd send out requests then? It seems to only 
> do so every
> once in a while, and if I'm not dialed in at that time, it fails.

So what?  It doesn't matter if it fails.  It doesn't set the clock to zero,
after all.  It just doesn't set it.

If it really makes a difference to you, have the appropriate stop and start
daemon commands in the scripts that execute upon bringup/bringdown of the
dialup interface... then it runs when you're connected and doesn't when you
aren't.

David

Re: [OT] Achieving Time-Synch at mailserver

[Peter van Dijk]

On Thu, Sep 21, 2000 at 04:38:02PM +0100, James Raftery wrote:
> On Thu, Sep 21, 2000 at 05:12:32PM +0200, Peter van Dijk wrote:
> > But when does xntpd send out requests then? It seems to only do so every
> > once in a while, and if I'm not dialed in at that time, it fails.
> 
> I don't know any more accurately than 'periodically'. My system
> clock doesn't run away with itself into oblivion, so I can live without
> a time sync on every dial-up. I imagine it can be made poll more often,
> either with a configuration option or some magic with the xntpdc
> program.

 minpoll minpoll
 maxpoll maxpoll
 These options specify the minimum and maximum polling in-
 tervals for NTP messages, in seconds to the power of two.
 The default range is 6 (64 s) to 10 (1,024 s).  The al-
 lowable range is 4 (16 s) to 17 (36.4 h) inclusive.

>From man ntp.conf on my FreeBSD 4.0-STABLE box. 1024s should do for me.

Greetz, Peter.
-- 
[ircoper][EMAIL PROTECTED] - Peter van Dijk / Hardbeat
[student]Undernet:#groningen/wallops | IRCnet:/#alliance
[developer]  EFnet:#qmail  _
[disbeliever - the world is backwards](__VuurWerk__(--*-

Re: [OT] Achieving Time-Synch at mailserver

[James Raftery]

On Thu, Sep 21, 2000 at 05:12:32PM +0200, Peter van Dijk wrote:
> But when does xntpd send out requests then? It seems to only do so every
> once in a while, and if I'm not dialed in at that time, it fails.

I don't know any more accurately than 'periodically'. My system
clock doesn't run away with itself into oblivion, so I can live without
a time sync on every dial-up. I imagine it can be made poll more often,
either with a configuration option or some magic with the xntpdc
program.

ATB,

james
-- 
James Raftery (JBR54)  -  Programmer Hostmaster  -  IE TLD Hostmaster
   IE Domain Registry  -  www.domainregistry.ie  -  (+353 1) 706 2375
  "Managing 4000 customer domains with BIND has been a lot like
   herding cats." - Mike Batchelor, on [EMAIL PROTECTED]

Re: [OT] Achieving Time-Synch at mailserver

[Chris Garrigues]

> From:  Peter van Dijk <[EMAIL PROTECTED]>
> Date:  Thu, 21 Sep 2000 17:12:32 +0200
>
> On Thu, Sep 21, 2000 at 03:58:45PM +0100, James Raftery wrote:
> > On Thu, Sep 21, 2000 at 11:39:32AM -0300, martin langhoff wrote:
> > >   The other machine has a intermittent connection, so I'm looking for a
> > > way to synchronize on a command (instead of a daemon).
> > 
> > The xntp package includes ntpdate. It does just this.
> > 
> > >   Am I too misguided? How are you guys keeping machines in synch?
> > 
> > xntpd, even on dial-up machines.
> 
> But when does xntpd send out requests then? It seems to only do so every
> once in a while, and if I'm not dialed in at that time, it fails.

You can set the period in the configuration file.  I believe the default is 
every 64 seconds (needs to be a power of 2).

Chris

-- 
Chris Garrigues http://www.DeepEddy.Com/~cwg/
virCIO  http://www.virCIO.Com
4314 Avenue C   
Austin, TX  78751-3709  +1 512 374 0500

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  explanation of what we're doing, see http://www.DeepEddy.Com/tms.html 

Nobody ever got fired for buying Microsoft,
  but they could get fired for relying on Microsoft.



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Re: [OT] Achieving Time-Synch at mailserver

[Peter van Dijk]

On Thu, Sep 21, 2000 at 03:58:45PM +0100, James Raftery wrote:
> On Thu, Sep 21, 2000 at 11:39:32AM -0300, martin langhoff wrote:
> > The other machine has a intermittent connection, so I'm looking for a
> > way to synchronize on a command (instead of a daemon).
> 
> The xntp package includes ntpdate. It does just this.
> 
> > Am I too misguided? How are you guys keeping machines in synch?
> 
> xntpd, even on dial-up machines.

But when does xntpd send out requests then? It seems to only do so every
once in a while, and if I'm not dialed in at that time, it fails.

Greetz, Peter.
-- 
[ircoper][EMAIL PROTECTED] - Peter van Dijk / Hardbeat
[student]Undernet:#groningen/wallops | IRCnet:/#alliance
[developer]  EFnet:#qmail  _
[disbeliever - the world is backwards](__VuurWerk__(--*-

Re: [OT] Achieving Time-Synch at mailserver

[James Raftery]

On Thu, Sep 21, 2000 at 11:39:32AM -0300, martin langhoff wrote:
>   The other machine has a intermittent connection, so I'm looking for a
> way to synchronize on a command (instead of a daemon).

The xntp package includes ntpdate. It does just this.

>   Am I too misguided? How are you guys keeping machines in synch?

xntpd, even on dial-up machines.

Regards,

james
-- 
James Raftery (JBR54)  -  Programmer Hostmaster  -  IE TLD Hostmaster
   IE Domain Registry  -  www.domainregistry.ie  -  (+353 1) 706 2375
  "Managing 4000 customer domains with BIND has been a lot like
   herding cats." - Mike Batchelor, on [EMAIL PROTECTED]