Mapr signals an alarm in the web ui when there are files in a nodes 
    /opt/cores dir.  This is anoying because we can't see if there is a real 
    problem with the node because of this pointless error message.  
    This removes those files so the alarm goes away.

def __CleanUpRootPartition(self):
    """ 
    Mapr signals an alarm in the web ui when there are files in a nodes 
    /opt/cores dir.  This is anoying because we can't see if there is a real 
    problem with the node because of this pointless error message.  
    This removes those files so the alarm goes away.
    """
    instances = self.__GetAllInstances()
    clean_cores_cmd = """sudo sh -c 'rm -rf /opt/mapr/cache/tmp/*'"""
    self.__RunCommandOnInstances(clean_cores_cmd, instances)
    return