Affects Version/s: 2.7.2
Fix Version/s: None
Under replicated blocks are not getting re-replicated
In production Hadoop cluster of 5 Manangement + 5 Data Nodes, under replicated blocks are not re-replicated even after 2 days.
Here is quick view of required configurations;
Default replication factor: 3
Average block replication: 3.0
Corrupt blocks: 0
Missing replicas: 0 (0.0 %)
Number of data-nodes: 5
Number of racks: 1
After bringing one of the DataNodes down, the replication factor for the blocks allocated on the Data Node became 2. It is observed that, even after 2 days the replication factor remains as 2. Under replicated blocks are not getting re-replicated to another DataNodes in the cluster.
If a Data Node goes down, HDFS will try to replicate the blocks from Dead DN to other nodes and the priority. Are there any configuration changes to speed up the re-replication process for the under replicated blocks?
When tested for blocks with replication factor 1, the re-replication happened to 2 overnight in around 10 hours of time. But blocks with 2 replication factor are not being re-replicated to default replication factor 3.