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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1726) query method for what kind of safe mode the Namenode is in
Date Fri, 13 Jul 2012 17:39:35 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13413896#comment-13413896
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Steve Loughran commented on HDFS-1726:
--------------------------------------

It'd be nice to also have text for end users, which could also be set in a manual entry mode.
This would let the ops teams add text like "down for rack maintenance back at 18:00" for the
web UI and exception text

                
> query method for what kind of safe mode the Namenode is in
> ----------------------------------------------------------
>
>                 Key: HDFS-1726
>                 URL: https://issues.apache.org/jira/browse/HDFS-1726
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: name-node
>    Affects Versions: 0.22.0
>            Reporter: Matt Foley
>            Assignee: Matt Foley
>             Fix For: 0.24.0
>
>         Attachments: SafeModeState_v2.patch
>
>
> If we could differentiate between "startup safemode" vs other safemode, it would be easier
to do startup optimizations like HDFS-1295.  Looking at FSNamesystem, this can be queried,
but not with a single query, and the semantics are not reliable under future changes.  Also,
the FSNamesystem code itself, internally, uses more than one way to test for manual safe mode.
> Proposal is to create a status field and query method in FSNamesystem with enum values
>     {NOT_IN_SAFEMODE, SAFEMODE_STARTUP, SAFEMODE_EXTENSION, SAFEMODE_MANUAL}
> If in the future we add automatic fallback to safe mode, we would add value SAFEMODE_AUTOMATIC.
> This change will make it easier to do startup optimizations, and will also allow making
the safemode management code in FSNamesystem simpler and more consistent.

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