[jboss-user] [Clustering/JBoss] - Re: Pooling in Buddy Replication

[bstansberry@jboss.com]

A key thing to understand is that if you'd killed *both* node1 and node2 at the same time, the data would have been lost. This would be the case even if all 4 nodes had the same buddy pool, but node2 had happened to pick node1.

Even if node1 and node2 were not killed at the same time, but node1 was killed before you'd accessed the session again somewhere, the data would have been lost.  See http://www.jboss.com/index.html?module=bb&op=viewtopic&t=99251 for a discussion of why that is.

A third scenario:

1) Start on node2.  The buddy is node1 since they have the same pool name.
2) Kill node1.
3) Kill node2.
4) Make another request.  Should work.  This is because when you killed node1, node2 detected that and chose another buddy.  So your session would have been backed up on node3 or 4, and would still be available.


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