'Get the size of the volume from the array.
:param array: the array serial number
:param device_id: the volume device id
:returns: size --  or None'

def get_size_of_device_on_array(self, array, device_id):

    cap = None
    try:
        vol = self.get_volume(array, device_id)
        cap = vol['cap_gb']
    except Exception as e:
        LOG.error('Error    retrieving    size    of    volume    %(vol)s.    Exception    received    was    %(e)s.', {'vol': device_id, 'e': e})
    return cap
