'Returns the serveros instance id of the specified osname.
Required to create a Dell server object.
We do not know that we are Red Hat Linux 6.x but that works
best for Red Hat and Ubuntu.  So we use that.
:param osname: The name of the OS to look for.
:param ssn: ssn of the backend SC to use. Default if -1.
:returns: InstanceId of the ScServerOperatingSystem object.'

def _find_serveros(self, osname='Red    Hat    Linux    6.x', ssn=(-1)):

    ssn = self._vet_ssn(ssn)
    pf = self._get_payload_filter()
    pf.append('scSerialNumber', ssn)
    r = self.client.post('StorageCenter/ScServerOperatingSystem/GetList', pf.payload)
    if self._check_result(r):
        oslist = self._get_json(r)
        for srvos in oslist:
            name = srvos.get('name', 'nope')
            if (name.lower() == osname.lower()):
                return self._get_id(srvos)
    LOG.warning('Unable    to    find    appropriate    OS    %s', osname)
    return None
