RE: [chrony-users] Isolated time domains

[Chris Dore <Chris.Dore@xxxxxxxxx>]

> It is very confusing what you want to do.
> the purpose of chrony is to discipline the clock on the computer to the best
> estimate of UTC that it can. You seem to want something else. What do you
> want?

Summary; I want the clients to sync to the master server's local clock and I have a need to optionally sync the master server to some offsite servers.  I don't want any offsite notion of time to leak onsite other than by moving the master server's local clock.  Perhaps also my choice of the words "master server" was misleading.  Each remote site has a master server for that site.  There is currently no single master server controlling time for all remote sites, that is what I'm working on deploying with some specific requirements that the internal systems of each remote site stay in sync locally while being moved in line with each other over time.

> > I'm working with systems of networked computers that are deployed into
> remote sites with potentially spotty internet access as well as clocks that
> have been manually maintained by field staff for decades.  I'm looking into
> bringing all these remote sites in synch with our main data centre.
> 
> I assume that your main data center is on UTC.

Maybe, maybe not.  It has an NTP server that is serving what it says is UTC and the remote servers follow it.

> > Currently there is a master server at each site that maintains time with the
> other nodes via NTP.  The server is currently serving up its local system clock
> via ntpd and the local system clock is set manually by field staff.
> 
> You mean that the master server's clock is manually set?

Yes, currently the master server at each remote site is set manually.

> > I would like to correct the clock on these master servers via NTP, while
> continuing to have to the other client nodes synchronize to the master
> server's local clock.
> 
> Above you said you wanted all the clocks to synced to the data center. Now
> you
> seem to be saying something else.

Eventually they will all be synced to the data centre, just that the clients internal to each remote site should not be directly syncing with the data centre.

> > I have Chrony on the master server configured with some remote servers
> as well as the "local" config option.  The clients are using a mix of Chrony and
> other NTP clients and are all configured to reference just the master server.
> 
> What clients? You mean the other computers in a cluster apart from the
> master
> in that cluster?

Hopefully I've made this clear already.

> > In my test setup I have the master server's clock set back about 3 hours and
> Chrony appears to be working great and is moving time towards what is
> reported by the external NTP servers:
> 
> Why? Is this a rediculous test? Why would you expect the master server to
> be 3
> hours out?

It is a test to help try and understand the behaviour of chrony without looking at the source code.  In the real word each remote site's master server is likely within 15mins of UTC at the moment.

> > However, I need the clients of the master server to remain synchronizing
> against the master server's local clock and not the NTP time reported by the
> external servers.  Looking at the chronyd instance running on one of my
> clients, it appears that the master server's chronyd is acting more like a proxy
> for the external servers:
> 
> So you do NOT want the clients to be synced to the database? Why do you
> want
> them synced to the master rather than to UTC?

Each system in a remote site needs to be in sync with each other. That is priority #1. Being in sync with UTC is not as important and has functioned that way for a long time.


Regards, Chris


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