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https://issues.apache.org/jira/browse/HDFS-2141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13067965#comment-13067965
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Konstantin Shvachko commented on HDFS-2141:
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Could you please clarify your terminology. What is a daemon, a role, and a
state?
We used to say that we start NameNode in active, backup, or checkpoint role.
Active is the default, if you do not specify the role. The command is:
{{hadoop namenode -backup}}
Don't see any confusion here.
Same with standby. It is a role of the NameNode. You can go from standby to
active. And may be vice versa at some point.
Do you want to change this terminology. How? Why?
Seems like you want to introduce a state in addition to the role, so that a
daemon in role NN could have two states active and standby. This IS really
confusing to me.
> 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.
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