[rabbitmq-discuss] Clustering Serwer Question

Wed Dec 1 10:16:25 GMT 2010

Hi,

> My question is how can i change a cluster type from ram to disk? I have 
> 2 serwers and 1 node in each of them. Need I have 3 servers to do it 
> like in tutorial http://www.rabbitmq.com/clustering.html#creating?

The nodes are either ram or disc.  When you issue the cluster command,
the nodes passed as arguments are the disc nodes.  From the clustering
guide,

rabbit2$ rabbitmqctl cluster rabbit at rabbit1
Clustering node rabbit at rabbit2 with [rabbit at rabbit1] ...done.

rabbit1$ rabbitmqctl status
Status of node rabbit at rabbit1 ...
[...,
  {nodes,[{disc,[rabbit at rabbit1]},{ram,[rabbit at rabbit2]}]},
  {running_nodes,[rabbit at rabbit2,rabbit at rabbit1]}]
...done.

rabbit2$ rabbitmqctl status
Status of node rabbit at rabbit2 ...
[...,
  {nodes,[{disc,[rabbit at rabbit1]},{ram,[rabbit at rabbit2]}]},
  {running_nodes,[rabbit at rabbit1,rabbit at rabbit2]}]
...done.

In the above example, we create a cluster of two nodes, rabbit1 is disc
(because it's in the arguments to the cluster command), and rabbit2 is
ram.

Two nodes is enough for a cluster.

> If I have persistent queue declared od serwer 1 when serwer 1 is down in 
> second serwer this queue dissappear. When I will change cluster typ this 
> behavior will change? Is it possible change it behavior about persistent 
> queue when serwers are in cluster?

No.

A queue can only exist on one node at a time.  If said node dies, the
queue disappears or becomes unusable: durable queues become unusable
until the node comes back online (they cannot be redeclared on another
node), non-durable queues just disappear (but can be redeclared on
another node).

If you need to not lose messages and have the queue available even after
a node death, you might want to have a look at the HA with Rabbit guide:
  http://www.rabbitmq.com/pacemaker.html

Cheers,
Alex

On Wed, Dec 01, 2010 at 10:03:04AM +0100, Adam Kaminiecki wrote:
> Hi,
> 
> My question is how can i change a cluster type from ram to disk? I have 
> 2 serwers and 1 node in each of them. Need I have 3 servers to do it 
> like in tutorial http://www.rabbitmq.com/clustering.html#creating?
> 
> 
> Another question is:
> If I have persistent queue declared od serwer 1 when serwer 1 is down in 
> second serwer this queue dissappear. When I will change cluster typ this 
> behavior will change? Is it possible change it behavior about persistent 
> queue when serwers are in cluster?
> 
> 
> 
> Regards,
> Adam
> 
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