Occasionally we see some blocks remain to be under-replicated in our production clusters. This is what we obeserved:
1. Sometimes when increasing the replication factor of a file, some blocks belonged to this file do not get to increase to the new replication factor.
2. When taking meta save in two different days, some blocks remain in under-replication queue.
- relates to
HADOOP-5479 NameNode should not send empty block replication request to DataNode