KrzyCube wrote:
    I found that "File[] editFiles" in FSEditLog.java , then i trace the
call stack and found that it can be configured as multi-case of
"dfs.name.dir" . Is this means the NameNode data can be split into pieces or
just set replication as the number of the strings of dirs that configured ?
    Is that right the way to backup several copys of the editlog+fsimage in
local filesystem ?

According to the documentation for dfs.name.dir:

http://lucene.apache.org/hadoop/hadoop-default.html#dfs.name.dir

  Determines where on the local filesystem the DFS name node should
  store the name table. If this is a comma-delimited list of directories
  then the name table is replicated in all of the directories, for
  redundancy.

Note that as of release 0.11 there's support for a secondary namenode, started with 'bin/hadoop secondarynamenode'.

http://issues.apache.org/jira/browse/HADOOP-227#action_12458332

This documentation should probably be added to http://lucene.apache.org/hadoop/hdfs_design.html, or at least to the wiki...

Doug

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