Dave Latham created HBASE-9888:
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             Summary: HBase replicates edits written before the replication 
peer is created
                 Key: HBASE-9888
                 URL: https://issues.apache.org/jira/browse/HBASE-9888
             Project: HBase
          Issue Type: Bug
            Reporter: Dave Latham


When creating a new replication peer the ReplicationSourceManager enqueues the 
currently open HLog to the ReplicationSource to ship to the destination 
cluster.  The ReplicationSource starts at the beginning of the HLog and ships 
over any pre-existing writes.

A workaround is to roll all the HLogs before enabling replication.

A little background for how it affected us - we were migrating one cluster in a 
master-master pair.  I.e. transitioning from A <-> B to B <-> C.  After 
shutting down writes from A -> B we enabled writes from C -> B.  However, this 
replicated some earlier writes that were in C's HLogs that had originated in A. 
 Since we were running a version of HBase before HBASE-7709 those writes then 
got caught in a infinite replication cycle and bringing down region servers OOM 
because of HBASE-9865.

However, in general, if one wants to manage what data gets replicated, one 
wouldn't expect that potentially very old writes would be included when setting 
up a new replication link.



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