hadoop secondnamenode配置

   一、secondnamenode是做什么的

    

 The Secondary Namenode is a helper to the primary Namenode.
 The Secondary is responsible for supporting periodic checkpoints
 of the HDFS metadata. The current design allows only one Secondary
 Namenode per HDFs cluster.

 The Secondary Namenode is a daemon that periodically wakes
 up (determined by the schedule specified in the configuration),
 triggers a periodic checkpoint and then goes back to sleep.
 The Secondary Namenode uses the ClientProtocol to talk to the
 primary Namenode.

 

 

 

   二、将hadoop的namenode和secondnamenode分离在不同的服务器上

   

   1. master

    将secondnamenode的ip配置在master中

   2.hdfs-site.xml

      将namenode配置在hdfs-site.xml中

<property> 
  <name>dfs.http.address</name> 
  <value>slave-01:50070</value> 
  <description> 
    The address and the base port where the dfs namenode web ui will listen on. 
    If the port is 0 then the server will start on a free port. 
  </description> 
</property>

    3.core-site.xml

<property> 
  <name>fs.checkpoint.period</name> 
  <value>3600</value> 
  <description>The number of seconds between two periodic checkpoints. 
  </description> 
</property>

<property> 
  <name>fs.checkpoint.size</name> 
  <value>67108864</value> 
  <description>The size of the current edit log (in bytes) that triggers 
       a periodic checkpoint even if the fs.checkpoint.period hasn't expired. 
  </description> 
</property>

    fs.checkpoint.period表示多长时间记录一次hdfs的镜像

    fs.checkpoint.size表示一次记录多大的size，默认64M