2017-03-13 18:23:11,852 INFO [namenode1:60000.activeMasterManager-SendThread(app2:2181)] zookeeper.ClientCnxn: Opening socket connection to server app2/10.226.21.35:2181. Will not attempt to authenticate using SASL (unknown error)
2017-03-13 18:23:11,853 WARN [namenode1:60000.activeMasterManager-SendThread(app2:2181)] zookeeper.ClientCnxn: Session 0x235ab6bb507e19e5 for server null, unexpected error, closing socket connection and attempting reconnect
java.net.ConnectException: 拒绝连接
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:350)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)
2017-03-13 18:23:12,030 INFO [namenode1:60000.activeMasterManager-SendThread(app3:2181)] zookeeper.ClientCnxn: Opening socket connection to server app3/10.226.21.36:2181. Will not attempt to authenticate using SASL (unknown error)
2017-03-13 18:23:12,031 WARN [namenode1:60000.activeMasterManager-SendThread(app3:2181)] zookeeper.ClientCnxn: Session 0x235ab6bb507e19e5 for server null, unexpected error, closing socket connection and attempting reconnect
java.net.ConnectException: 拒绝连接
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:350)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)
2017-03-13 18:23:12,061 INFO [main-SendThread(app3:2181)] zookeeper.ClientCnxn: Opening socket connection to server app3/10.226.21.36:2181. Will not attempt to authenticate using SASL (unknown error)
2017-03-13 18:23:12,062 WARN [main-SendThread(app3:2181)] zookeeper.ClientCnxn: Session 0x235ab6bb507e19e2 for server null, unexpected error, closing socket connection and attempting reconnect
java.net.ConnectException: 拒绝连接
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
hbase报此类错误是因为，zookeeper停掉了，必须先把hadoop和zookeeper启动好，然后启动HBase
原文：http://www.cnblogs.com/alexwu59/p/6544613.html