I have 4 same configured nodes and one has a SSH issue during the verification step in the MapR installer. Message:
"fatal: [dedcm4249] => SSH Error: data could not be sent to the remote host. Make sure this host can be reached over ssh. Host: dedcm4249 is unreachable".
I'm working with clustershell (which use SSH also) without Problems (e.g. clush -w dedcm4249 "ls -al").
Logging in with "ssh dedcm4249" from another node is possible too.
Any idea why MapR can't do this?