hi, guys. I want to move all the blocks from 50 datanodes to another 50 new datanodes. There is a very easy idea that we can add the new 50 nodes to hadoop cluster firstly, then decommission the other 50 nodes one by one. But, I believe it is not an efficient way to reach the goal. So I plan to get the help of the idea of Hdfs balancer, which limits the movements happen to the 100 nodes. But I need to disable write_op for those nodes to be decommissioned.
Is there a way to make DataNode in safe mode (read only) mode? Of course, regarding to blocks movement between nodes, Any thoughts will be appreciated. -- Bing Jiang
