Remotely collect server data using Net::OpenSSH Perl
Looks good to me. Kudos for the "... or die" idiom. More informative output would be "unable to run df on $s" or "unable to run svmon on $s".

You don't have to do tail or grep on the far end, as a line of perl could do that. But it is a perfectly clean and sensible approach, which I advocate keeping.

If you wind up with many such monitoring commands, you may find it convenient to move the post-processing into perl commands that can be refactored out as utility functions.