qpid-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ken Giusti <kgiu...@redhat.com>
Subject Re: Questions from a novice
Date Tue, 02 Apr 2013 13:07:29 GMT


----- Original Message -----
> From: "Bill Freeman" <ke1g.nh@gmail.com>
> To: users@qpid.apache.org
> Sent: Monday, April 1, 2013 7:50:16 PM
> Subject: Re: Questions from a novice
> 
> Ken,
> 
> 
> On Mon, Apr 1, 2013 at 5:58 PM, Ken Giusti <kgiusti@redhat.com> wrote:
> 
> > > That sounds delux, since they would probably even survive moving a broker
> > > from one server to another (with a different IP address.
> >
> > Whoa, moving a broker won't guarantee the fed-tag would be the same :(
> >
> > You see, the fed-tag is written to disk by the broker at startup, so it
> > can be preserved across restarts.  But if you move the broker to a new
> > machine, and it cannot find the fed-tag it has written to disk, it will
> > create a new one.  Not something you'd want.  You'd have to move the
> > contents of the working directory along with it.
> >
> 
> 
> I presume it's written to the data directory, yes?   So if the data
> directory is copied, it should keep its tag?  Or is this a bad idea because
> the data directory thinks it knows IP addresses of other federation members
> (like Vulcan), even if they were originally specified by DNS name?  (The
> moving is not particularly important.  I'm just trying to see how much
> state I can keep if a box dies and the broker gets moved pending
> replacement.)
> 

Just to be complete - yes, the generated tag is written to the data dir used by the qpidd
daemon.  You can control the location of this file using --data-dir command line option or
config file entry.   Currently, the only stuff stored in that file shouldn't depend on the
original DNS name, ip address, etc.  So you should be safe moving that data dir when you move
the broker.

But, having said that, my own personal preference would be to configure a federation tag on
a per broker instance, and assign that via the qpidd.conf file.  It just seems less error
prone, but this is just my gut feel.  I would do this by hand-generating a unique UUID for
each broker (using whatever uuid generating tools you prefer), then dole them out.  But I'm
a bit of a control freak :)

> 
> 
> >
> > You can assign a "static" fed-tag to a broker using the federation-tag
> > configuration option (either on the command line or via the qpid.config
> > file).  If you deploy that way you have total control over how the fed-tag
> > is used.
> >
> 
> 
> This sounds like a reasonable policy for us.
> 
> 
> 
> >
> > And to be clear, if a broker is a member of a federation, then the tag is
> > required.  And it must be unique across all brokers reachable by the
> > federation.  And the tag isn't modified by the brokers, so it will be
> > consistent across all brokers in the federation.
> >
> 
> 
> Good!
> 
> 
> >
> > FYI: opened a jira on that console.py issue:
> > https://issues.apache.org/jira/browse/QPID-4689
> >
> 
> 
> Thanks for that.
> 
> 
> And thanks in general.

My pleasure!

> 
> Bill
> 

-- 
-K

---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@qpid.apache.org
For additional commands, e-mail: users-help@qpid.apache.org


Mime
View raw message