Details
Major Description
Currently HDFS snapshot diff report can identify file/directory creation, deletion, rename and modification under a snapshottable directory. We can use the diff report for distcp between the primary cluster and a backup cluster to avoid unnecessary data copy. This is especially useful when there is a big directory rename happening in the primary cluster: the current distcp cannot detect the rename op thus this rename usually leads to large amounts of real data copy.
More details of the approach will come in the first comment.