[jira] Commented: (HDFS-1726) query method for what kind of safe mode the Namenode is in

["Aaron T. Myers (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-1726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13003023#comment-13003023 ] 

Aaron T. Myers commented on HDFS-1726:
--------------------------------------

HDFS-1594 could make use of the proposed SAFEMODE_AUTOMATIC status.

> 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: 0.23.0
>
>
> 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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