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https://issues.apache.org/jira/browse/HDFS-2141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13068567#comment-13068567
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Suresh Srinivas commented on HDFS-2141:
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Let me answer it in different order:
bq. "What is wrong with current terminology and why it needs to be changed?"
Current NameNode roles are ACTIVE, STANDBY, BACKUP and CHECKPOINT
Are all these namenodes? If there is STANDBY already what is the role of
BACKUP? In my terminology, CHECKPOINT would not be a state, do you allow any of
the roles to transition to CHECKPOINT? ACTIVE and STANDBY are the states
related to HA. The others are related to functionality provided by a process.
There is no reason to mix the two.
bq. What state machine? A two state machine? Do you plan to share the design?
Please see HDFS-1974. I will add design details soon. But the initial version
of the patch should give you an idea. Currently it has two states - Active and
Standby.
> 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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