[ https://issues.apache.org/jira/browse/HDFS-2141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13068084#comment-13068084 ]
Todd Lipcon commented on HDFS-2141: ----------------------------------- Having just worked on some code in the BN recently, I agree with Suresh. The inheritance structure is error prone here and has resulted in bugs. For example, in trunk today, "hadoop fs -ls" against a BackupNode succeeds, whereas "hadoop fs -stat" or any other read operations fails with an exception that the BN does not support these operations. This is because of the inheritance structure - it's too easy to modify the NN in such a way that introduces issues in the BN (the "fragile base class" issue) > Remove NameNode roles Active and Standby (they become states) > ------------------------------------------------------------- > > Key: HDFS-2141 > URL: https://issues.apache.org/jira/browse/HDFS-2141 > Project: Hadoop HDFS > Issue Type: Sub-task > Components: name-node > Reporter: Suresh Srinivas > Assignee: Suresh Srinivas > Fix For: 0.23.0 > > Attachments: HDFS-2141.1.patch, HDFS-2141.patch > > > In HDFS, following roles are supported in NameNodeRole: ACTIVE, BACKUP, > CHECKPOINT and STANDBY. > Active and Standby are the state of the NameNode. While Backup and CheckPoint > are the name/role of the daemons that are started. This mixes up the run time > state of NameNode with the daemon role. I propose changing the NameNodeRole > to: NAMENODE, BACKUP, CHECKPOINT. HDFS-1974 will introduce the states active > and standby to the daemon that is running in the role NAMENODE. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira