Michi Mutsuzaki created ZOOKEEPER-1653: ------------------------------------------
Summary: zookeeper fails to start because of inconsistent epoch Key: ZOOKEEPER-1653 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1653 Project: ZooKeeper Issue Type: Bug Components: quorum Affects Versions: 3.4.5 Reporter: Michi Mutsuzaki It looks like QuorumPeer.loadDataBase() could fail if the server was restarted after zk.takeSnapshot() but before finishing self.setCurrentEpoch(newEpoch). {code:java} case Leader.NEWLEADER: // it will be NEWLEADER in v1.0 zk.takeSnapshot(); self.setCurrentEpoch(newEpoch); // <<< got restarted here snapshotTaken = true; writePacket(new QuorumPacket(Leader.ACK, newLeaderZxid, null, null), true); break; {code} The server fails to start because currentEpoch is still 1 but the last processed zkid from the snapshot has been updated to 2. {noformat} 2013-02-20 13:45:02,733 5543 [pool-1-thread-1] ERROR org.apache.zookeeper.server.quorum.QuorumPeer - Unable to load database on disk java.io.IOException: The current epoch, 1, is older than the last zxid, 8589934592 at org.apache.zookeeper.server.quorum.QuorumPeer.loadDataBase(QuorumPeer.java:439) at org.apache.zookeeper.server.quorum.QuorumPeer.start(QuorumPeer.java:413) ... {noformat} {noformat} $ find datadir datadir datadir/version-2 datadir/version-2/currentEpoch.tmp datadir/version-2/acceptedEpoch datadir/version-2/snapshot.0 datadir/version-2/currentEpoch datadir/version-2/snapshot.200000000 $ cat datadir/version-2/currentEpoch.tmp 2% $ cat datadir/version-2/acceptedEpoch 2% $ cat datadir/version-2/currentEpoch 1% {noformat} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira