问题：执行[root@node01 hadoop-2.6.0-cdh5.14.0]# sbin/start-dfs.sh 后，namenode未启动

执行[root@node01 hadoop-2.6.0-cdh5.14.0]# sbin/start-dfs.sh 后，namenode未启动。

解决步骤：

查看/export/servers/hadoop-2.6.0-cdh5.14.0/logs/hadoop-root-namenode-node01.hadoop.com.log日志文件，发现报错信息：

2019-05-22 00:52:44,132 WARN org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Encountered exception lo

ading fsimage

java.io.IOException: NameNode is not formatted.

2019-05-22 00:52:44,251 ERROR org.apache.hadoop.hdfs.server.namenode.NameNode: Failed to start namenode.

java.io.IOException: NameNode is not formatted.

原因：namenode未格式化。

解决方案：

三台机器上，递归删除以下目录删除：

rm -rf /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/

三台机器上，重新创建以下目录：

mkdir -p /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/tempDatas

mkdir -p /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/namenodeDatas

mkdir -p /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/datanodeDatas

mkdir -p /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/dfs/nn/edits

mkdir -p /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/dfs/snn/name

mkdir -p /export/servers/hadoop-2.6.0-cdh5.14.0/hadoopDatas/dfs/nn/snn/edits

node01上，执行bin/hdfs namenode  -format

node01上，执行：

cd /export/servers/hadoop-2.6.0-cdh5.14.0/

sbin/start-dfs.sh

sbin/start-yarn.sh

sbin/mr-jobhistory-daemon.sh start historyserver