[jboss-dev-forums] [Design of Clustering on JBoss (Clusters/JBoss)] - Re: Handling cluster state when network partitions occur

[bstansberry@jboss.com]

The "merge state" approach gets another wrinkle when you factor in buddy replication"

1) Good.  If you're holding buddy backup data for a node that wasn't in your subpartition (i.e. D has A's backup data when the split was {A B C} {D E}) then when you get the MergeView and you see A was still there, you should be able to safely discard your old backup of A's data.

2) Bad. With total replication, the subpartition coordinators can handle the state merging task, since they have a copy of all the data (e.g. A and D could compare state).  With buddy replication, everyone has to reconcile with all nodes in the foreign partition, since any one of them could have become an owner of data during the split (D reconciles with A,B,C; E reconciles with A,B,C).


The above is not the same when data partitioning is used instead of buddy replication. Since the goal is to replace BR with data partitioning, maybe we will end not having to worry about the BR wrinkles. :)

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