Why do we need Hadoop passwordless ssh?

Question

• AFAIK, passwordless ssh is needed so that the master node can start the daemon processes on each slave node. Apart from that, is there any use of having passwordless ss

Answer 1

Answer to the first question:

The Hadoop core uses Shell (SSH) to launch the server processes on the slave nodes. It requires password-less SSH connection between the master and all the slaves and the secondary machines.

We need a password-less SSH in a Fully-Distributed environment because when the cluster is LIVE and running in Fully Distributed environment, the communication is too frequent. The job tracker should be able to send a task to task tracker quickly.