9a6d8e70_Hadoop_Commands_Guide__Description
[COMMAND_OPTION] -metasave filename [Description] 
Save Namenode's primary data structures to filename in the directory specified by hadoop.log.dir property. filename will contain one line for each of the following 1. Datanodes heart beating with Namenode 2. Blocks waiting to be replicated 3. Blocks currrently being replicated 4. Blocks waiting to be deleted
Hadoop Commands Guide