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From Paul Gale <>
Subject Re: difficult and unusual configuration..
Date Mon, 13 May 2013 02:01:22 GMT
>I saw this document from here and i think in here they
allow brokers to have more than 2.
>Did i misunderstand what you mean?

In master-slave you can have as many brokers as you want, regardless of the
storage strategy in use. However, there can only be one master at any one
instant in time. The other brokers will remain slaves. As slaves they have
their transport connectors turned so as not to accept any client
connections. They are also constantly trying to acquire the shared lock
that the master hold. If the master dies one of the slaves will be
successful in its next attempt to acquire the lock as the master will not
have been able to renew its lease on the lock. Once acquired the slave
holding the lock will automatically promote itself to become the new master
at which point it will turn on its transport connectors and start accepting
client connections.

One requirement for all this to work is that all clients must be using the
failover protocol to connect to a broker. In turn all clients using the
failover protocol must know the addresses of all the brokers as
load-balancing is done client-side; an unfortunate consequence of using the
failover protocol. I suppose you could mitigate this by putting all the
brokers behind a load-balancer and have all clients use a single VIP
although how the load-balancer would know which broker was the new master
is not clear to me.

At least that's how I've always understood it.

Feel free to correct any errors.


On Sun, May 12, 2013 at 8:24 PM, verystrongjoe <>wrote:

> thanks for reply.
> so you mean the master/slave have to configured with only 2 brokers?
> I saw this document from ( here
> <>  )
> and i think in here they allow brokers to have more than 2.
> did i misunderstand what you mean?
> and how about using vm connector and putting the jdbc persistent adaptor to
> each broker?
> --
> View this message in context:
> Sent from the ActiveMQ - User mailing list archive at

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