关于Hadoop secondarynamenode概念
根据文档 (http://hadoop.apache.org/common/docs/r0.20.203.0/hdfs_user_guide.html) secondarynamenode 在 hadoop0.20.203.0 版本中已弃用，并由 checkpointnode 和 backupnode 取代。但在集群设置文档（http://hadoop.apache.org/common/docs/r0.20.203.0/cluster_setup.html）中没有提到该更改。更多关于 bin/start-dfs.sh 在 conf/masters 文件中提到的地址中启动 secondaryname 节点。
有人可以提供有什么区别吗？这是否意味着配置没有改变。仅 secondarynamenode 的内部架构被更改。
此外，在 hadoop0.23.0 版本上，没有用于指定辅助名称节点需要启动的主机地址的 conf/masters 文件。
谢谢 MRK
As per the documnetation (http://hadoop.apache.org/common/docs/r0.20.203.0/hdfs_user_guide.html) secondarynamenode is deprecated in hadoop0.20.203.0 release onwards and replaced by checkpointnode and backupnode. But in cluster set up doc (http://hadoop.apache.org/common/docs/r0.20.203.0/cluster_setup.html) no where mentioned about that change. More over bin/start-dfs.sh starting secondaryname node in the address mentioned in conf/masters file.
Can some one provide what is difference? Does it mean configuration not changed. only internal architecture of secondarynamenode is chnaged..
Also on hadoop0.23.0 release there is no conf/masters file where we used to specify the host address where secondary name node needs to start.
Thanks
MRK
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0.23 的文档有点稀疏，我不得不深入研究代码。在 DFSConfigKeys.java 已定义以下变量。在 hdfs-site.xml 中将 dfs.namenode. secondary.http-address 密钥设置为 ip:port 并使用 sbin/hadoop-daemon.sh start secondarynamenode 启动辅助名称节点代码>命令。运行 jps 命令来检查辅助名称节点是否正在运行，并确保检查日志文件是否有任何错误。
公共静态最终字符串DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY =“dfs.namenode.secondary.http-address”;
辅助神经网络被称为检查点神经网络。但是，代码仍然使用辅助 NN，人们仍然将其称为辅助 NN。
相关的 HDFS-2141 Jira 的描述来看
从与 0.23 版本 Active Standby是NameNode的状态。而 Backup 和 CheckPoint 是启动的守护进程的名称/角色。
The documentation for 0.23 is a bit sparse and I had to dig through the code. In the DFSConfigKeys.java the below variables have been defined. Set the
dfs.namenode.secondary.http-addresskey to ip:port in hdfs-site.xml and start the secondary namenode using thesbin/hadoop-daemon.sh start secondarynamenodecommand. Run jps command to check if the secondary namenode is running and also make sure to check the log file also for any errors.public static final String DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY = "dfs.namenode.secondary.http-address";
Secondary NN is being called CheckPoint NN. But, the code is still using Secondary NN and people still refer it as Secondary NN.
From the description of the HDFS-2141 Jira which is related to 0.23 release
Active and Standby are the state of the NameNode. While Backup and CheckPoint are the name/role of the daemons that are started.