Index: hbase-common/src/main/resources/hbase-default.xml =================================================================== --- hbase-common/src/main/resources/hbase-default.xml (revision 1511512) +++ hbase-common/src/main/resources/hbase-default.xml (working copy) @@ -283,12 +283,16 @@ zookeeper.session.timeout 90000 - ZooKeeper session timeout. - HBase passes this to the zk quorum as suggested maximum time for a - session (This setting becomes zookeeper's 'maxSessionTimeout'). See - http://hadoop.apache.org/zookeeper/docs/current/zookeeperProgrammers.html#ch_zkSessions - "The client sends a requested timeout, the server responds with the - timeout that it can give the client. " In milliseconds. + ZooKeeper session timeout in milliseconds. It is used in two different ways. + First, this value is used in the ZK client that HBase uses to connect to the ensemble. + It is also used by HBase when it starts a ZK server and it is passed as the 'maxSessionTimeout'. See + http://hadoop.apache.org/zookeeper/docs/current/zookeeperProgrammers.html#ch_zkSessions. + For example, if a HBase region server connects to a ZK ensemble that's also managed by HBase, then the + session timeout will be the one specified by this configuration. But, a region server that connects + to an ensemble managed with a different configuration will be subjected that ensemble's maxSessionTimeout. So, + even though HBase might propose using 90 seconds, the ensemble can have a max timeout lower than this and + it will take precedence. The current default that ZK ships with is 40 seconds, which is lower than HBase's. + zookeeper.znode.parent