hadoop升级
首先停机，更新namenode,datanode上hadoop，然后
namenode节点上进行:
915 hadoop namenode -upgrade
916 hadoop namenode -rollback
917 hadoop namenode -upgrade
918 hadoop dfsadmin -finalizeUpgrade
919 hadoop namenode -upgrade
914 hadoop dfsadmin -upgradeProgress status
datanode上进行:
396 hadoop datanode -upgrade
397 hadoop datanode -rollback
398 hadoop datanode -upgrade
399 hadoop DataNode -upgrade
400 hadoop datanode -upgrade
401 tail -f /opt/modules/hadoop/logs/hadoop-root-datanode-data-test-209.log
402 hadoop datanode -upgrade
403 hadoop datanode -rollback
404 hadoop datanode -finalized
