Below an excerpt from a single node zk quorum that was at heart of a small hbase cluster. Unfortunately the log is not at DEBUG level (I've asked the gentleman to up the log level meantime). What it seems to be reporting is that an exception while closing a session caused it to timeout all connected sessions.
Here is the line that mentions the exception on close of session. There is no stack trace: 2009-11-20 03:41:04,766 WARN org.apache.zookeeper.server.NIOServerCnxn: Exception causing close of session 0x124bc250d700790 due to java.io.IOException: Read error Is it correct that an error at this stage throws out all connected sessions? Thanks, St.Ack 2009-11-20 00:00:04,948 INFO org.apache.zookeeper.server.NIOServerCnxn: Connected to /10.1.20.101:50716 lastZxid 0 2009-11-20 00:00:04,982 INFO org.apache.zookeeper.server.NIOServerCnxn: Creating new session 0x1250f26319f0016 2009-11-20 00:00:05,051 INFO org.apache.zookeeper.server.NIOServerCnxn: Finished init of 0x1250f26319f0016 valid:true 2009-11-20 00:00:05,051 WARN org.apache.zookeeper.server.PrepRequestProcessor: Got exception when processing sessionid:0x1250f26319f0016 type:create c xid:0x1 zxid:0xfffffffffffffffe txntype:unknown n/a org.apache.zookeeper.KeeperException$NodeExistsException: KeeperErrorCode = NodeExists at org.apache.zookeeper.server.PrepRequestProcessor.pRequest(PrepRequestProcessor.java:245) at org.apache.zookeeper.server.PrepRequestProcessor.run(PrepRequestProcessor.java:114) 2009-11-20 00:00:40,150 WARN org.apache.zookeeper.server.PrepRequestProcessor: Got exception when processing sessionid:0x1250f26319f0016 type:create c xid:0x4 zxid:0xfffffffffffffffe txntype:unknown n/a org.apache.zookeeper.KeeperException$NodeExistsException: KeeperErrorCode = NodeExists at org.apache.zookeeper.server.PrepRequestProcessor.pRequest(PrepRequestProcessor.java:245) at org.apache.zookeeper.server.PrepRequestProcessor.run(PrepRequestProcessor.java:114) 2009-11-20 00:00:50,428 WARN org.apache.zookeeper.server.NIOServerCnxn: Exception causing close of session 0x1250f26319f0016 due to java.io.IOExceptio n: Read error 2009-11-20 00:00:50,429 INFO org.apache.zookeeper.server.NIOServerCnxn: closing session:0x1250f26319f0016 NIOServerCnxn: java.nio.channels.SocketChann el[connected local=/10.1.20.101:2181 remote=/10.1.20.101:50716] 2009-11-20 00:01:22,002 INFO org.apache.zookeeper.server.SessionTrackerImpl: Expiring session 0x1250f26319f0016 2009-11-20 00:01:22,002 INFO org.apache.zookeeper.server.ZooKeeperServer: Expiring session 0x1250f26319f0016 2009-11-20 00:01:22,002 INFO org.apache.zookeeper.server.PrepRequestProcessor: Processed session termination request for id: 0x1250f26319f0016 2009-11-20 03:41:04,766 WARN org.apache.zookeeper.server.NIOServerCnxn: Exception causing close of session 0x124bc250d700790 due to java.io.IOExceptio n: Read error 2009-11-20 03:41:04,864 INFO org.apache.zookeeper.server.SessionTrackerImpl: Expiring session 0x1250f26319f0000 2009-11-20 03:41:04,927 INFO org.apache.zookeeper.server.ZooKeeperServer: Expiring session 0x1250f26319f0000 2009-11-20 03:41:04,927 INFO org.apache.zookeeper.server.SessionTrackerImpl: Expiring session 0x124bc250d7007a2 2009-11-20 03:41:04,927 INFO org.apache.zookeeper.server.ZooKeeperServer: Expiring session 0x124bc250d7007a2 2009-11-20 03:41:04,927 INFO org.apache.zookeeper.server.SessionTrackerImpl: Expiring session 0x124bc250d700794 2009-11-20 03:41:04,927 INFO org.apache.zookeeper.server.ZooKeeperServer: Expiring session 0x124bc250d700794