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From Gary Tully <gary.tu...@gmail.com>
Subject Re: what about Slave failing in "Pure-Master Slave" setup?
Date Fri, 18 Jun 2010 13:32:07 GMT
This is true, pure master slave is asymmetrical and it requires manual
intervention to restore the paring once the master fails. There is an option
on the broker to have the master shutdown if the slave fails, but this is
off by default. The problem is that there is currently no way to have a
slave connect and play catch up with an already running and active master.

Most folk use the shared data store fault tolerant strategy. where N brokers
can share a data store (shared file system or jdbc) and one broker gains an
exclusive lock and becomes active. the rest become passive slaves.

(That said, from looking at the code, the master will carry on (without the
slave) if it fails to replicate an async command but does not stop
replication on the failure of a  sync command, which is a little bogus. It
should just ignore the slave if any replication attempt fails. If you have a
use case for pure master slave, please open a jira issue so we can ensure a
master can carry on in the event of a slave failure)


On 18 June 2010 14:10, Oleg Kiorsak <kiorsak@gmail.com> wrote:

>
>
> One of the benefits of Pure Master Slave are that supposedly it provides
> some "HA" -
> namely books, tutorials, wiki site describe that "when MASTER fails SLAVE"
> becomes a MASTER
> and clients are smoothly reconnected to it via the virtue of "failover
> transport"...
>
> That is all nice and good, and TRUE (I tested it)
>
> But the question arises - what if its the SLAVE one that fails (as it is a
> 50/50 chance)...
>
> In my testing (when I "kill -KILL") the SLAVE's process the end result is
> that MASTER just stops accepting any connections and even the queues even
> disappear from JMX jConsole....
>
> only the restart of both restores "status quo"... but restart is something
> that has to be done manually...
>
>
> so as far as "HA" the solution seems to be asymmetrical - is is only an
> "HA"
> when it is the MASTER that fails first...
>
> Am I missing something?
>
> ???
>
> Is there maybe some way to configure it so that MASTER continues to work...
> alone (just as the SLAVE would if MASTER failed)...
> ??
>
>
> cheers,
> O.K.
>
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> --
> View this message in context:
> http://old.nabble.com/what-about-Slave-failing-in-%22Pure-Master-Slave%22-setup--tp28925866p28925866.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
>


-- 
http://blog.garytully.com

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