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My HBase cluster refused to start after upgrading from CDH3 to CDH4. This is a known issue according to the cloudera documentation, and the workaround is to delete the /hbase ZNode.

— During an upgrade from CDH3 to CDH4, regions in transition may cause HBase startup failures.

Bug: None
Severity: Medium
Anticipated Resolution: To be fixed in a future release.
Workaround: Delete the /hbase ZNode in ZooKeeper before starting up CDH4.

So to delete the ZNode I did the following:

[root@hbase1 ~]# /usr/lib/zookeeper/bin/zkCli.sh
Connecting to localhost:2181
... log entries
[zk: localhost:2181(CONNECTED) 0] rmr /hbase

After doing this the cluster started as it should.
Ref: http://www.cloudera.com/content/cloudera-content/cloudera-docs/CDH4/4.3.0/CDH4-Release-Notes/cdh4ki_topic_1_11.html

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§567 · oktober 2, 2013 · Hadoop, HBase, ZooKeeper · (No comments) · Tags: , , , ,