[rabbitmq-discuss] Is the "master" node mandatory ?

Matthew Sackman matthew at rabbitmq.com
Tue Oct 19 17:35:16 BST 2010

On Tue, Oct 19, 2010 at 06:28:47PM +0200, Vincent Barat wrote:
> My two nodes are RAM nodes actually.

Ahh. From http://rabbitmq.com/clustering.html:

"Because state is replicated across all nodes in the cluster, it is
sufficient to have just one disk node within a cluster, to store the
state of the cluster safely. Beware, however, that RabbitMQ will not
stop you from creating a cluster with only RAM nodes. Should you do
this, and suffer a power failure to the entire cluster, the entire state
of the cluster, including all messages, will be lost."

I think we used to prevent you from building RAM-node-only clusters. We
must have changed behaviour there a while ago. It makes sense that the
last node to die needs to be brought up first: if a node goes down and
it knew that it was part of a cluster, then when coming back up, it'll
remember it was part of a cluster and try to reconnect to it - it will
be very aware that any data it holds (in this case, none!) will likely
be out of date and it needs to resync from the other nodes in the
cluster - it'll have no knowledge that the other nodes also went down.

That said, it's been a while since I played around with clusters so my
information might be out of date.


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