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

[Ajit Ratnaparkhi]

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.