zk数据文件读取异常(Unable to load database on disk)

现象：zookeeper无法启动；

异常：Unable to load database on disk；

原因：数据文件读取异常，缺失则无法启动；

解决：在zk数据文件存放目录下（见 $ZK/conf/zoo.cfg，dataDir和dataLogDir属性），删除version-2文件夹。再重启zk。

异常贴下：

2014-09-24 14:01:30,558 [myid:11] - ERROR [main:QuorumPeer@453] - Unable to load database on disk
java.io.IOException: Failed to process transaction type: 1 error: KeeperErrorCode = NoNode for /crxj/intercept
    at org.apache.zookeeper.server.persistence.FileTxnSnapLog.restore(FileTxnSnapLog.java:153)
    at org.apache.zookeeper.server.ZKDatabase.loadDataBase(ZKDatabase.java:223)
    at org.apache.zookeeper.server.quorum.QuorumPeer.loadDataBase(QuorumPeer.java:417)
    at org.apache.zookeeper.server.quorum.QuorumPeer.start(QuorumPeer.java:409)
    at org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:151)
    at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:111)
    at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:78)
Caused by: org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode for /crxj/intercept
    at org.apache.zookeeper.server.persistence.FileTxnSnapLog.processTransaction(FileTxnSnapLog.java:211)
    at org.apache.zookeeper.server.persistence.FileTxnSnapLog.restore(FileTxnSnapLog.java:151)
    ... 6 more