RE: What does hdfs balancer do after adding more disks to existing datanode.

[Uma Maheswara Rao G <ma...@huawei.com>]

Hi,

Current volume choosing policy is round robin fashion, Since the DN got new disk, balancer will balance some blocks to this node. But the volume choosing will be same when palcing the block. AFAIK, it wont do any special balancing between disks in the same node. please correct me if i understood your question wrongly.





Regards,

Uma



From: Ajit Ratnaparkhi [ajit.ratnaparkhi@gmail.com]
Sent: Tuesday, November 22, 2011 5:13 PM
To: hdfs-user@hadoop.apache.org; hdfs-dev@hadoop.apache.org
Subject: What does hdfs balancer do after adding more disks to existing datanode.


Hi,

If I add additional disks to existing datanode (assume existing datanode has 7 1TB disk which are already 80% full and then I add two new 2TB disks 0% full) and then run balancer, does balancer balance data in a datanode? ie. Will it move data from existing disks to newly added disks such that all disks are approx equally full ?

thanks,
Ajit.