HDFS-1171 since RAID is in mapreduce)
RaidNode currently does not fix missing blocks. The missing blocks have to be fixed using RaidShell.
This task proposes that recovery be more automated:
1. RaidNode periodically fetches a list of corrupt files from the NameNode
2. If the corrupt files can be fixed using RAID, it should generate the block.
3. Choose a datanode and send the block contents along with checksum to the datanode.