Robo copy may be http://www.robocopy.net which appears to be an online backup facility. If that's the case, the outcome of using robocopy may be different than the outcome of copying a file from one server to another with a Perl script. robocopy probably moves the file to www.robocopy.net's online backup servers, which he probably couldn't do without using their proprietary software. ...all this is speculation of course, but I'm guessing that if the server admins wish that he use a specific online backup service instead of his script, the decision isn't really his anyway, and even if it were, he's not really comparing apples with apples.