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From "Suresh Srinivas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2141) Remove NameNode roles Active and Standby (they become states)
Date Wed, 20 Jul 2011 21:47:58 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13068662#comment-13068662

Suresh Srinivas commented on HDFS-2141:

> "The NameNode in HDFS, in addition to its primary role serving client requests, can alternatively
execute either of two other roles, either a CheckpointNode or a BackupNode. The role is specified
at the node startup..." Go to Chapter 9.2.5.
First, this is before HA. Second, I do not parse role as strictly as you are.

> Can you live with roles, without renaming 2 of them into states? I think it is an unnecessary
change in terminology, which involved code change.
I prefer states, because these are truly states. I associate more permanent association of
a process to a role, unlike state changes. As a product evolves, things change. It would be
better to use the correct abstractions than try to keep a doc from getting outdated.

> 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
> 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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