搭建zookeeper集群环境后，启动zookeeper

[root@Node4 bin]# ./zkServer.sh start

运行结果如下：

JMX enabled by default
Using config: /usr/zoo/zookeeper-3.4.5/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

 显示以为启动成功，实则不然

[root@Node4 bin]# ./zkServer.sh stuts

结果如下：

JMX enabled by default
Using config: /usr/zoo/zookeeper-3.4.5/bin/../conf/zoo.cfg
Error contacting service. It is probably not running.

可见，zk未成功启动

./zkServer.sh start-foreground  

结果如下：

JMX enabled by default
Using config: /usr/zoo/zookeeper-3.4.5/bin/../conf/zoo.cfg
2017-05-16 07:45:29,742 [myid:] - INFO  [main:QuorumPeerConfig@101] - Reading configuration from: /usr/zoo/zookeeper-3.4.5/bin/../conf/zoo.cfg
2017-05-16 07:45:29,746 [myid:] - INFO  [main:QuorumPeerConfig@334] - Defaulting to majority quorums
2017-05-16 07:45:29,764 [myid:1] - INFO  [main:DatadirCleanupManager@78] - autopurge.snapRetainCount set to 3
2017-05-16 07:45:29,764 [myid:1] - INFO  [main:DatadirCleanupManager@79] - autopurge.purgeInterval set to 0
2017-05-16 07:45:29,764 [myid:1] - INFO  [main:DatadirCleanupManager@101] - Purge task is not scheduled.
2017-05-16 07:45:29,787 [myid:1] - INFO  [main:QuorumPeerMain@127] - Starting quorum peer
2017-05-16 07:45:29,802 [myid:1] - INFO  [main:NIOServerCnxnFactory@94] - binding to port 0.0.0.0/0.0.0.0:2181
2017-05-16 07:45:29,833 [myid:1] - INFO  [main:QuorumPeer@913] - tickTime set to 2000
2017-05-16 07:45:29,833 [myid:1] - INFO  [main:QuorumPeer@933] - minSessionTimeout set to -1
2017-05-16 07:45:29,833 [myid:1] - INFO  [main:QuorumPeer@944] - maxSessionTimeout set to -1
2017-05-16 07:45:29,834 [myid:1] - INFO  [main:QuorumPeer@959] - initLimit set to 10
2017-05-16 07:45:29,865 [myid:1] - INFO  [main:QuorumPeer@444] - acceptedEpoch not found! Creating with a reasonable default of 0. This should only happen when you are upgrading your installation
2017-05-16 07:45:29,894 [myid:1] - INFO  [Thread-1:QuorumCnxManager$Listener@486] - My election bind port: 0.0.0.0/0.0.0.0:3888
2017-05-16 07:45:29,906 [myid:1] - INFO  [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:QuorumPeer@670] - LOOKING
2017-05-16 07:45:29,908 [myid:1] - INFO  [QuorumPeer[myid=1]/0:0:0:0:0:0:0:0:2181:FastLeaderElection@740] - New election. My id =  1, proposed zxid=0x0
2017-05-16 07:45:29,915 [myid:1] - INFO  [WorkerReceiver[myid=1]:FastLeaderElection@542] - Notification: 1 (n.leader), 0x0 (n.zxid), 0x1 (n.round), LOOKING (n.state), 1 (n.sid), 0x0 (n.peerEPoch), LOOKING (my state)
2017-05-16 07:45:29,928 [myid:1] - WARN  [WorkerSender[myid=1]:QuorumCnxManager@368] - Cannot open channel to 2 at election address /192.168.0.113:3888
java.net.NoRouteToHostException: 没有到主机的路由 (Host unreachable)
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:354)
	at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:327)
	at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:393)
	at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:365)
	at java.lang.Thread.run(Thread.java:745)
2017-05-16 07:45:29,973 [myid:1] - WARN  [WorkerSender[myid=1]:QuorumCnxManager@368] - Cannot open channel to 3 at election address /192.168.0.114:3888

或者使用如下命令来查看zk的启动参数：

./zkServer.sh print-cmd 

更为重要的是可以通过zookeeper启动日志来查看，在/zookeeper-3.4.5/bin中

root@Node5 bin]# cat zookeeper.out 
2017-05-16 07:42:10,739 [myid:] - INFO  [main:QuorumPeerConfig@101] - Reading configuration from: /usr/zoo/zookeeper-3.4.5/bin/../conf/zoo.cfg
2017-05-16 07:42:10,743 [myid:] - INFO  [main:QuorumPeerConfig@334] - Defaulting to majority quorums
2017-05-16 07:42:10,758 [myid:3] - INFO  [main:DatadirCleanupManager@78] - autopurge.snapRetainCount set to 3
2017-05-16 07:42:10,759 [myid:3] - INFO  [main:DatadirCleanupManager@79] - autopurge.purgeInterval set to 0
2017-05-16 07:42:10,759 [myid:3] - INFO  [main:DatadirCleanupManager@101] - Purge task is not scheduled.
2017-05-16 07:42:10,778 [myid:3] - INFO  [main:QuorumPeerMain@127] - Starting quorum peer
2017-05-16 07:42:10,793 [myid:3] - INFO  [main:NIOServerCnxnFactory@94] - binding to port 0.0.0.0/0.0.0.0:2181
2017-05-16 07:42:10,819 [myid:3] - INFO  [main:QuorumPeer@913] - tickTime set to 2000
2017-05-16 07:42:10,819 [myid:3] - INFO  [main:QuorumPeer@933] - minSessionTimeout set to -1
2017-05-16 07:42:10,819 [myid:3] - INFO  [main:QuorumPeer@944] - maxSessionTimeout set to -1
2017-05-16 07:42:10,819 [myid:3] - INFO  [main:QuorumPeer@959] - initLimit set to 10
2017-05-16 07:42:10,842 [myid:3] - INFO  [main:QuorumPeer@444] - acceptedEpoch not found! Creating with a reasonable default of 0. This should only happen when you are upgrading your installation
2017-05-16 07:42:10,855 [myid:3] - INFO  [Thread-1:QuorumCnxManager$Listener@486] - My election bind port: 0.0.0.0/0.0.0.0:3888
2017-05-16 07:42:10,867 [myid:3] - INFO  [QuorumPeer[myid=3]/0:0:0:0:0:0:0:0:2181:QuorumPeer@670] - LOOKING
2017-05-16 07:42:10,868 [myid:3] - INFO  [QuorumPeer[myid=3]/0:0:0:0:0:0:0:0:2181:FastLeaderElection@740] - New election. My id =  3, proposed zxid=0x0
2017-05-16 07:42:10,877 [myid:3] - WARN  [WorkerSender[myid=3]:QuorumCnxManager@368] - Cannot open channel to 1 at election address /192.168.0.112:3888
java.net.NoRouteToHostException: 没有到主机的路由 (Host unreachable)
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:354)
	at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:327)
	at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:393)
	at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:365)
	at java.lang.Thread.run(Thread.java:745)
2017-05-16 07:42:11,882 [myid:3] - WARN  [WorkerSender[myid=3]:QuorumCnxManager@368] - Cannot open channel to 2 at election address /192.168.0.113:3888

基于以上错误提示，定位解决方案：

1、zookeeper集群间的leader和follower互ping不同

2、防火墙是否关闭

以下针对不同版本的Linux系统检查防火墙的状态，及关闭防火墙：

---------------------------------------------------------------

Ubuntu（ubuntu-12.04-desktop-amd64）

查看防火墙状态：ufw status

关闭防火墙：ufw disable

---------------------------------------------------------------

centos6.0

查看防火墙状态：service iptables status

关闭防火墙：chkconfig iptables off    #开机不启动防火墙服务

--------------------------------------------------------------

centos7.0(默认是使用firewall作为防火墙，如若未改为iptables防火墙，使用以下命令查看和关闭防火墙)

查看防火墙状态：firewall-cmd --state

关闭防火墙：systemctl stop firewalld.service

我的是centos7，却使用service iptables status等centos6的命令检查和关闭防火墙，导致防火墙实际上未关闭，故而出现以上错误