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From "Dave Latham (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-9888) HBase replicates edits written before the replication peer is created
Date Mon, 04 Nov 2013 18:09:19 GMT
Dave Latham created HBASE-9888:

             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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