As part of the "Version upgrade" related changes, thinking of strictly
requiring that datanode be able to lock _all_ the configured directories
instead of any one of them.
Currently if multiple data directories are specified for a datanode, it
tries to lock a file is in each of the directories. If it fails to lock
some of the directories, it will use the directories that it could.
Looks like this flexibility was included mainly for convenience in
config file.
This might not affect anyone, let us know of your opinions.
Note that all directories have the same storage id. So each individual
directory is not complete by itself but a part of one storage.
Raghu.
