[jira] [Created] (KAFKA-691) Fault tolerance broken with replication factor 1

["Jay Kreps (JIRA)" <ji...@apache.org>]

Jay Kreps created KAFKA-691:
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             Summary: Fault tolerance broken with replication factor 1
                 Key: KAFKA-691
                 URL: https://issues.apache.org/jira/browse/KAFKA-691
             Project: Kafka
          Issue Type: Bug
    Affects Versions: 0.8
            Reporter: Jay Kreps


In 0.7 if a partition was down we would just send the message elsewhere. This meant that the partitioning was really more of a "stickiness" then a hard guarantee. This made it impossible to depend on it for partitioned, stateful processing.

In 0.8 when running with replication this should not be a problem generally as the partitions are now highly available and fail over to other replicas. However in the case of replication factor = 1 no longer really works for most cases as now a dead broker will give errors for that broker.

I am not sure of the best fix. Intuitively I think this is something that should be handled by the Partitioner interface. However currently the partitioner has no knowledge of which nodes are available. So you could use a random partitioner, but that would keep going back to the down node.



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