'Check if LU exists on appliance.
:param zvol_name: Zvol name
:raises NexentaException: if zvol not exists
:return: True if LU exists, else False'

def _lu_exists(self, zvol_name):

    try:
        return bool(self.nms.scsidisk.lu_exists(zvol_name))
    except exception.NexentaException as exc:
        if ('does    not    exist' not in exc.args[0]):
            raise
        return False
