Look at the hadoop balancer - it will live data around and balance it across the nodes.
Sent from the wilds on my BlackBerry smartphone. From: Manoj Venkatesh Sent: Friday, February 6, 2015 5:54 PM To: user@hadoop.apache.org Reply To: user@hadoop.apache.org Subject: Adding datanodes to Hadoop cluster - Will data redistribute? Dear Hadoop experts, I have a Hadoop cluster of 8 nodes, 6 were added during cluster creation and 2 additional nodes were added later to increase disk and CPU capacity. What i see is that processing is shared amongst all the nodes whereas the storage is reaching capacity on the original 6 nodes whereas the newly added machines have relatively large amount of storage still unoccupied. I was wondering if there is an automated or any way of redistributing data so that all the nodes are equally utilized. I have checked for the configuration parameter - dfs.datanode.fsdataset.volume.choosing.policy have options 'Round Robin' or 'Available Space', are there any other configurations which need to be reviewed. Thanks, Manoj