I'm able to remote login the target host with ssh. But when I execute a command through pdsh, it fails with connection refused. Both systems are sles11.I found a description of the error on this page as follows.Message:pdsh@local_hostname: target_hostname:connect: Connection refused    Cause:The target system is unreachable, or the r services may be disabled for this system.    To Correct:Check the r services and whether the target system is up and connected.In my case, the target system is up so the cause should be the disabled r services.So what are r services and how could I enable it?
pdsh command failed with connection refused
ssh;sles
pdsh uses rsh by default, not ssh. Rsh, rlogin and rcmd are the r services; they are deprecated and your system rightly doesn't have them available. Ssh is the modern alternative to the r services; it is preferred because it encrypts and authenticates connections (and also because it's more flexible than the old, quirky r commands). Tell pdsh to use ssh:pdsh -R ssh or set the PDSH_RCMD_TYPE environment variable to ssh:export PDSH_RCMD_TYPE=sshpdsh 