Specifying racks for hosts

HDFS uses the network location of your deployment, such as hosts and racks, to place block replicas more intelligently and trade off performance and resilience. When placing jobs on hosts, CDP prefers within-rack transfers, where there is more bandwidth available, to off-rack transfers. These computations are performed with the assistance of rack awareness scripts. Cloudera Manager includes internal rack awareness scripts, but you must specify the racks where the hosts in your cluster are located.

  1. In Cloudera Manager, go to Hosts > All Hosts.
  2. Select the checkboxes corresponding to the hosts for which you want to specify the racks.
  3. Select Actions for Selected > Assign Rack.
  4. Enter a rack name or ID that begins with a slash (/); for example, /rack123 or /aisle1/rack123, and click Confirm.
  5. Restart the affected services.