[jira] [Created] (HBASE-12070) Add an option to hbck to fix ZK inconsistencies

["Sudarshan Kadambi (JIRA)" <ji...@apache.org>]

Sudarshan Kadambi created HBASE-12070:
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             Summary: Add an option to hbck to fix ZK inconsistencies
                 Key: HBASE-12070
                 URL: https://issues.apache.org/jira/browse/HBASE-12070
             Project: HBase
          Issue Type: Bug
            Reporter: Sudarshan Kadambi


If the HMaster bounces in the middle of table creation, we could be left in a state where a znode exists for the table, but that hasn't percolated into META or to HDFS. We've run into this a couple times on our clusters. Once the table is in this state, the only fix is to rm the znode using the zookeeper-client. Doing this manually looks a bit error prone. Could an option be added to hbck to catch and fix such inconsistencies?

A more general issue I'd like comment on is whether it makes sense for HMaster to be maintaining its own write-ahead log? The idea would be that on a bounce, the master would discover it was in the middle of creating a table and either rollback or complete that operation? An issue that we observed recently was that a table that was in DISABLING state before a bounce was not in that state after. A write-ahead log to persist table state changes seems useful. Now, all of this state could be in ZK instead of the WAL - it doesn't matter where it gets persisted as long as it does.



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