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From Justin Bertram <jbert...@apache.org>
Subject Re: [ARTEMIS] Clustered broker with multiple live servers and shared JDBC-Store
Date Tue, 24 Apr 2018 16:45:28 GMT
> what I understood from the documentation is that with the scale-down
option it should very well be possible to offload the current work to
another live server (in case of normal shutdown, of course). Or am I wrong?

Your understanding is correct. However, scale-down and HA are not the same
thing although they are related. HA is to protect data in case of a broker
failure. The typical scale-down use case is for dynamic clusters where
nodes may be brought-up and then shut-down in response to increasing and
decreasing loads. Your previous message talked about HA and not scale-down
specifically.

> A client currently connected to a live server is being notified that this
server is going down and which server will take up the work. By what? The
connector-ref definition in some cluster configuration (which might not be
public accessable at all)? Or the public acceptor definition of the target
server?

Where the broker scales-down is determined by the configuration as outlined
in the documentation. I'm not sure what you mean by "public" in this
context.

> ...what happens to current transactions/messages in progress if I
shutdown (not abort) the live server?

It depends on your configuration. If you've set failover-on-shutdown = true
(as discussed in the documentation) then the backup will activate and all
your persistent data (including transaction state) will be available on the
backup. If failover-on-shutdown = false then the backup will not activate
and your persistent data will not be available again until you restart that
broker.

> What happens to messages which are not marked as PERSISTENT?

If you shutdown a broker without scale-down then all non-persistent data
will be lost. That's how non-persistent data works - it doesn't survive a
broker failure or restart.


Justin

On Tue, Apr 24, 2018 at 11:02 AM, Archibald <archi99@gmx.net> wrote:

> Hi Justin,
>
> what I understood from the documentation is that with the scale-down option
> it should very well be possible to offload the current work to another live
> server (in case of normal shutdown, of course). Or am I wrong?
>
> And how's scaled down interally handled? A client currently connected to a
> live server is being notified that this server is going down and which
> server will take up the work. By what? The connector-ref definition in some
> cluster configuration (which might not be public accessable at all)? Or the
> public acceptor definition of the target server?
>
> If I now change the environment to one live and one backup server with a
> shared storage (jdbc), what happens to current transactions/messages in
> progress if I shutdown (not abort) the live server?
> Will those be migrated to the backup server? What happens to messages which
> are not marked as PERSISTENT?
>
> Sorry for bothering with so many questions. But clustering is (was never)
> easy to implement...
>
> Br,
> A.
>
>
>
> --
> Sent from: http://activemq.2283324.n4.nabble.com/ActiveMQ-User-
> f2341805.html
>

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