安裝Hadoop的Tips

1. 先在一臺機器上(master)把配置修改好，在複製到其他節點上(slaves)

2. xxx-en.sh中需要配置JAVA_HOME爲jdk文件夾絕對路徑，不能用環境變量$JAVA_HOME

3. slaves文件中寫各個slaves的主機名或者IP

4. 注意主節點的主機名在/etc/hosts中和IP的對應關係

5. Starting namenodes on [master]
   
   master: ssh: connect to host master port 22: Connection timed out
   

   在/etc/hosts/文件中修改master的IP爲主節點IP，如果時在主節點上，可以是本機IP 127.0.0.1

6. 查看日誌datanode連接主節點9000端口失敗
   查看主節點端口狀態

   	archlab@h-hadoop-master:~/hyh/hadoop-2.7.7/sbin$ netstat -an | grep 9000
   tcp        0      0 127.0.0.1:9000          0.0.0.0:*               LISTEN     
   tcp        0      0 127.0.0.1:48354         127.0.0.1:9000          TIME_WAIT 
   

   修改主機節點/etc/hosts文件

   127.0.0.1       localhost
   #127.0.1.1      ceph-osd1
   #127.0.1.1      master
   192.168.30.184 h-hadoop-master
   #127.0.0.1 master
   192.168.30.184 master
   192.168.30.190 worker90
   192.168.30.191 worker91
   192.168.30.192 worker92
   192.168.30.193 worker93
   

   重新啓動後查看端口狀態

   archlab@h-hadoop-master:~/hyh/hadoop-2.7.7/sbin$ netstat -an | grep 9000
   archlab@h-hadoop-master:~/hyh/hadoop-2.7.7/sbin$ netstat -an | grep 9000
   tcp        0      0 192.168.30.184:9000     0.0.0.0:*               LISTEN     
   tcp        0      0 192.168.30.184:9000     192.168.30.191:49296    ESTABLISHED
   tcp        0      0 192.168.30.184:9000     192.168.30.193:42416    ESTABLISHED
   tcp        0      0 192.168.30.184:9000     192.168.30.192:52136    ESTABLISHED
   tcp        0      0 192.168.30.184:9000     192.168.30.190:56954    ESTABLISHED
   

   分別查看主節點和datanode的日誌，都正常。
   上傳文件並查看：

   archlab@h-hadoop-master:~/hyh/hadoop-2.7.7/sbin$ hadoop fs -put ~/hyh/jpg.tar.gz /
   archlab@h-hadoop-master:~/hyh/hadoop-2.7.7/sbin$ hadoop fs -ls /     
   Found 1 items
   -rw-r--r--   1 archlab supergroup  118373985 2019-03-08 14:05 /jpg.tar.gz