解決辦法
因為，如下，我的Hadoop HA集群。
1、首先在hdfs-site.xml中添加下面的參數，該參數的值默認為false：
<property>
<name>dfs.ha.automatic-failover.enabled.ns</name>
<value>true</value>
</property>
2、在core-site.xml文件中添加下面的參數，該參數的值為ZooKeeper服務器的地址，ZKFC將使用該地址。
在HA或者HDFS聯盟中，上面的兩個參數還需要以NameServiceID為后綴，比如dfs.ha.automatic-failover.enabled.mycluster。除了上面的兩個參數外，還有其它幾個參數用於自動故障轉移，比如ha.zookeeper.session-timeout.ms，但對於大多數安裝來說都不是必須的。
在添加了上述的配置參數后，下一步就是在ZooKeeper中初始化要求的狀態，可以在任一NameNode中運行下面的命令實現該目的，該命在ZooKeeper中創建znode：
執行該命令需要進入Hadoop的安裝目錄下面的bin目錄中找到hdfs這個命令，輸入上面的命令執行，然后就可以修復這個問題了。
注意：之前，先得啟動好，每台機器的zookeeper進程。
[kfk@bigdata-pro01 bin]$ pwd /opt/modules/hadoop-2.6.0/bin [kfk@bigdata-pro01 bin]$ ./hdfs zkfc -formatZK
18/06/16 10:44:28 INFO zookeeper.ZooKeeper: Initiating client connection, connectString=bigdata-pro01.kfk.com:2181,bigdata-pro02.kfk.com:2181,bigdata-pro03.kfk.com:2181 sessionTimeout=5000 watcher=org.apache.hadoop.ha.ActiveStandbyElector$WatcherWithClientRef@20deea7f 18/06/16 10:44:28 INFO zookeeper.ClientCnxn: Opening socket connection to server bigdata-pro01.kfk.com/192.168.80.151:2181. Will not attempt to authenticate using SASL (unknown error) 18/06/16 10:44:28 INFO zookeeper.ClientCnxn: Socket connection established to bigdata-pro01.kfk.com/192.168.80.151:2181, initiating session 18/06/16 10:44:28 INFO zookeeper.ClientCnxn: Session establishment complete on server bigdata-pro01.kfk.com/192.168.80.151:2181, sessionid = 0x164065bc2a90001, negotiated timeout = 5000 =============================================== The configured parent znode /hadoop-ha/ns already exists. Are you sure you want to clear all failover information from ZooKeeper? WARNING: Before proceeding, ensure that all HDFS services and failover controllers are stopped! =============================================== Proceed formatting /hadoop-ha/ns? (Y or N) 18/06/16 10:44:28 INFO ha.ActiveStandbyElector: Session connected. y 18/06/16 10:44:57 INFO ha.ActiveStandbyElector: Recursively deleting /hadoop-ha/ns from ZK... 18/06/16 10:44:57 INFO ha.ActiveStandbyElector: Successfully deleted /hadoop-ha/ns from ZK. 18/06/16 10:44:57 INFO ha.ActiveStandbyElector: Successfully created /hadoop-ha/ns in ZK. 18/06/16 10:44:57 INFO zookeeper.ClientCnxn: EventThread shut down 18/06/16 10:44:57 INFO zookeeper.ZooKeeper: Session: 0x164065bc2a90001 closed [kfk@bigdata-pro01 bin]$
啟動並測試
1、先停止掉Hadoop和zookeeper的進程。
2、啟動zookeeper進程。
3、開啟zkfc進程
[kfk@bigdata-pro01 hadoop-2.6.0]$ pwd /opt/modules/hadoop-2.6.0 [kfk@bigdata-pro01 hadoop-2.6.0]$ sbin/hadoop-daemon.sh start zkfc starting zkfc, logging to /opt/modules/hadoop-2.6.0/logs/hadoop-kfk-zkfc-bigdata-pro01.kfk.com.out
4、進入Hadoop的安裝目錄下面的sbin目錄中，找到start-dfs.sh命令可以啟動NameNode，當然這里需要你在配置了NameNode主節點的Hadoop節點上面來執行他。
或者，直接sbin/start-all.sh
[kfk@bigdata-pro02 hadoop-2.6.0]$ bin/hdfs -help
Usage: hdfs [--config confdir] COMMAND
where COMMAND is one of:
dfs run a filesystem command on the file systems supported in Hadoop.
namenode -format format the DFS filesystem
secondarynamenode run the DFS secondary namenode
namenode run the DFS namenode
journalnode run the DFS journalnode
zkfc run the ZK Failover Controller daemon
datanode run a DFS datanode
dfsadmin run a DFS admin client
haadmin run a DFS HA admin client
fsck run a DFS filesystem checking utility
balancer run a cluster balancing utility
jmxget get JMX exported values from NameNode or DataNode.
mover run a utility to move block replicas across
storage types
oiv apply the offline fsimage viewer to an fsimage
oiv_legacy apply the offline fsimage viewer to an legacy fsimage
oev apply the offline edits viewer to an edits file
fetchdt fetch a delegation token from the NameNode
getconf get config values from configuration
groups get the groups which users belong to
snapshotDiff diff two snapshots of a directory or diff the
current directory contents with a snapshot
lsSnapshottableDir list all snapshottable dirs owned by the current user
Use -help to see options
portmap run a portmap service
nfs3 run an NFS version 3 gateway
cacheadmin configure the HDFS cache
crypto configure HDFS encryption zones
storagepolicies get all the existing block storage policies
version print the version
Most commands print help when invoked w/o parameters.
[kfk@bigdata-pro02 hadoop-2.6.0]$
[kfk@bigdata-pro02 hadoop-2.6.0]$ bin/hdfs haadmin -help
Usage: DFSHAAdmin [-ns <nameserviceId>]
[-transitionToActive <serviceId> [--forceactive]]
[-transitionToStandby <serviceId>]
[-failover [--forcefence] [--forceactive] <serviceId> <serviceId>]
[-getServiceState <serviceId>]
[-checkHealth <serviceId>]
[-help <command>]
Generic options supported are
-conf <configuration file> specify an application configuration file
-D <property=value> use value for given property
-fs <local|namenode:port> specify a namenode
-jt <local|resourcemanager:port> specify a ResourceManager
-files <comma separated list of files> specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars> specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives> specify comma separated archives to be unarchived on the compute machines.
The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]
[kfk@bigdata-pro02 hadoop-2.6.0]$
注意，其實自帶的命令里，都提供了，若兩者都是standby狀態怎么執行。若兩者都是active狀態怎么執行。這里，不多贅述。
如果，還是沒解決的話，則
bin/hdfs haadmin -transitionToActive nn1
