If both the NameNode and the secondary NameNode were to suddenly go offline, you can
restore the NameNode.
-
Add a new host to your Hadoop cluster.
-
Add the NameNode role to the host. Make sure it has the same hostname as the original
NameNode.
-
Create a directory path for the NameNode
name.dir (for
example, /dfs/nn/current), ensuring that the permissions are set
correctly.
-
Copy the
VERSION and latest fsimage file to the
/dfs/nn/current directory.
-
Run the following command to create the md5 file for the fsimage.
md5sum fsimage > fsimage.md5
-
Start the NameNode process.
