[nycbug-talk] dealing with drift

[Jim Brown]

* Isaac Levy <ike at lesmuug.org> [2005-02-28 13:09]:
> Thanks yall',
> 
> On Feb 28, 2005, at 12:33 PM, George Georgalis wrote:
> 
> >>Hi All,
> >>
> >>I was just wanting to post on some of the post-meeting conversations
> >>I've repeatedly over-heard about managing time-drift across clusters 
> >>of
> >>machines- (you know who you people are...)
> >>
> >>How do folks like to do this?  Special tools beyond rockin' timed?
> >>Anyone know any good urls on the topic (either practical or acidemic)?
> >
> >Am I missing something here? Isn't the obvious answer, for a cluster, 
> >to
> >configure the headnode (whether is connected to internet and synced or
> >not) to answer ntp queries from nodes, and configure the nodes ntp time
> >server to use their headnode?  /usr/ports/net/ntp
> 
> On Feb 28, 2005, at 12:43 PM, Dan Langille wrote:
> 
> >Sounds like much the same way I manage my home network.  My gateway
> >acts as time master, and all other machines on my network sync with
> >it.  In turn, the gateway syncs with an external source.
> 
> 
> Cool.  My question then changes to this:
> 
> Are there any tricks to maintain redundancy with ntp servers?  i.e. is 
> there a builtin/traditional way to configure things so that *all* 
> machines can act as ntp servers in the event that the ntp box goes el' 
> muerte?

Simple suggestion:

  Pick 4 or more servers from the list at 
   http://ntp.isc.org/bin/view/Servers/StratumOneTimeServers
   (Use any 'OpenAccess' server listed.  If the server indicates
   that the maintainer would like to hear from you- send a courtesy
   email.  See the 'Rules Of Engagement' at
   http://ntp.isc.org/bin/view/Servers/RulesOfEngagement )

  One one machine, put two servers from the above list
     in the /etc/ntp.conf file.

     server one.someserver.com
     server two.someserver.com


  On another machine, put the other two servers from the above list
     in /etc/ntp.conf.

     server three.someserver.com
     server four.someserver.com

I actually use a pool of eight NTP stratum 1 servers, and have
four entries on each of my servers.

I also add a driftfile statement.  See ntp.conf(5) for details.

There are many options in ntp.conf, most of which you will never use.

For the truly paranoid, use authentication.  

Hope this helps,
Jim B.