Add the following config params:
- Max Disk Throughput - This allows users to control how much disk I/O is generated while disk balancer is running
- Max Disk Errors - For each move operation, this allows user to specify how many I/O failures are tolerated before we declare the operation as failed.
#Block Tolerance - Specifies how much movement of data is good enough. since the datanodes are active while the copy is going on, tolerance lets the user specify that if we reached something like 5% of projected Ideal storage on the destination disk, we can consider that move to be successful.
Each of these parameter can be specified for each MoveStep. if not specified then the config parameters are used.