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