: The Name Node is in-charge of ensuring each block always has the intended number of replicas. Every time a report
from a Data Node arrives, the Name Node will determine how many replicas each block has. If a block is under-replicated, it will get inserted in the replication priority queue. An over-replicated block will make the Name Node to remove one replica. If a replica resides on one rack and other replica is scheduled to be created on the same rack, the system will find a new rack to create the replica