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From "David Budworth" <>
Subject Re: temporary queue in store and forward environment
Date Thu, 03 May 2007 16:44:20 GMT
I have a question along these lines, you said here that there's no mechanism
to do real time broker-broker synchronization.

Does that imply that when starting up a master slave system, you must start
both the master and the slave before any clients start sending messages?  Or
if the master is up (and processing messages) the slave can be started at
any time and will get a state sync?

We've been looking at replacing SonicMQ with ActiveMQ for some specific
features that AMQ support, but one thing we rely on (on the Sonic side) is
their CAA stuff that gives the transparent failover and back.

we can live without the fail back and just restart the whole thing using a
manual rsync of the store from slave back to master, but if clients
reconnect and start sending as soon as the master is up, we'll have no
chance of getting the slave up.

Maybe I'm just misunderstanding here?

On 4/30/07, James Strachan <> wrote:
> On 4/29/07, DavidR <> wrote:
> >
> > Ok, so if we go back to Master Slave, then we have the following issue:
> > Currently we are using the JDBC Master Slave but we see this uses a lot
> of
> > CPU.
> > So, we would want to go to pure Master Slave.
> > So, can you help us understand the following: It says in the docs that
> if
> > one goes down "A failed master cannot be re-introduced without shutting
> down
> > the the slave broker". Can it be re-introduced as a slave without any
> > restart of the running queue?
> The issue is we don't have a real time broker-broker synchronization
> mechanism yet for pure master/slave. So you can start up 2 brokers in
> a master/slave; if the master fails the slave takes over just fine.
> But if you wish to introduce another slave/master to the master after
> failover, you need to stop the broker & copy its files to the new
> location. We don't yet have a way to dynamically bring a new cluster
> member online to a running cluster.
> >  Also, if the slave had items in the queue not
> > processes and then came up as slave, what would happen with those
> messages?
> All kinds of issues would arise if you brought up an old master/slave
> into a running master/slave cluster without synchronizing. e.g. ACKs
> could be missed so messages could be duplicated - plus messages could
> be lost.
> --
> James
> -------

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