1. Problem
After performing start-dfs.sh view jps in the process, found NameNode start, but no DataNode
2. reasons
See .log file failed inconsistencies clusterID and namenode of datanode of clusterID
The reason may be multiple Hadoop namenode -format lead to inconsistent clusterID
3. Solution
1) go profile hdfs-site.xml path seen in hadoop dfs.datanode.data.dir address and the address of the dfs.namenode.name.dir
默认：file://${hadoop.tmp.dir}/dfs/name、file://${hadoop.tmp.dir}/dfs/data
2) obtained in clusterID ... / name / current / VERSION of
[root@hadoop201 current]# more VERSION #Mon Sep 02 18:06:26 CST 2019 namespaceID=1033971221 clusterID=CID-98e754ef-ad92-49f8-88b2-6830888f2d48 cTime=0 storageType=NAME_NODE blockpoolID=BP-1400239548-192.168.1.201-1567418785939 layoutVersion=-63
3) The changes to the clusterID ... / dfs / data / current / VERSION
[root@hadoop201 current]# vi VERSION #Sun Sep 01 19:46:01 CST 2019 storageID=DS-330d79ed-7c1b-4d40-b151-81ffcadcf9f0 #clusterID=CID-ae479da3-0b1e-44b0-a383-029a213b3481 clusterID=CID-98e754ef-ad92-49f8-88b2-6830888f2d48 cTime=0 datanodeUuid=67fcc2ae-1b74-46cd-90df-336a0b1950e6 storageType=DATA_NODE layoutVersion=-56
4) Start DataNode again, the successful launch
[root@hadoop201 hadoop-2.7.2]# sbin/hadoop-daemon.sh start datanode starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-hadoop201.com.out [root@hadoop201 hadoop-2.7.2]# jps 11525 DataNode 10809 QuorumPeerMain 11001 NameNode 11598 Jps