If you accidentally deleted /root/.ssh directory, the automatic ssh key generator doesn't produce the right permission for all files. This causes a problem to ssh to nodes. In rocks cluster, the root account nodes have a different password (no one knows what it is exactly, since it is never generated or used).
You have to check the right permission :
chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_rsa
chmod 644 ~/.ssh/id_rsa.pub
chmod 644 ~/.ssh/authorized_keys
chmod 644 ~/.ssh/known_hosts
