configuration parameter to prevent accidental formatting of HDFS filesystem
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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
Priority: Minor
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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