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https://issues.apache.org/jira/browse/HDFS-718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12901498#action_12901498
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Jakob Homan commented on HDFS-718:
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One nit on patch: Since the patch was changed correctly to use the DFS
constants - {{DFS_NAMENODE_SUPPORT_ALLOWFORMAT_KEY =
"dfs.namenode.support.allowformat";}} - we should really reference this key
only through the constant and not directly. Otherwise, +1 as it is.
> configuration parameter to prevent accidental formatting of HDFS filesystem
> ---------------------------------------------------------------------------
>
> Key: HDFS-718
> URL: https://issues.apache.org/jira/browse/HDFS-718
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Affects Versions: 0.22.0
> Environment: Any
> Reporter: Andrew Ryan
> Assignee: Andrew Ryan
> Priority: Minor
> Attachments: HDFS-718.patch-2.txt, HDFS-718.patch.txt
>
>
> Currently, any time the NameNode is not running, an HDFS filesystem will
> accept the 'format' command, and will duly format itself. There are those of
> us who have multi-PB HDFS filesystems who are really quite uncomfortable with
> this behavior. There is "Y/N" confirmation in the format command, but if the
> formatter genuinely believes themselves to be doing the right thing, the
> filesystem will be formatted.
> This patch adds a configuration parameter to the namenode,
> dfs.namenode.support.allowformat, which defaults to "true," the current
> behavior: always allow formatting if the NameNode is down or some other
> process is not holding the namenode lock. But if
> dfs.namenode.support.allowformat is set to "false," the NameNode will not
> allow itself to be formatted until this config parameter is changed to "true".
> The general idea is that for production HDFS filesystems, the user would
> format the HDFS once, then set dfs.namenode.support.allowformat to "false"
> for all time.
> The attached patch was generated against trunk and +1's on my test machine.
> We have a 0.20 version that we are using in our cluster as well.
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