def METHOD_NAME(self, disk, oldkey):
    cmd = ['scu', '-f', disk, 'preserve', 'preempt', 'key', self.hostid, 'skey', oldkey, 'type', self.prtype]
    (ret, out, err) = self.vcall(cmd)
    if ret != 0:
        self.log.error("failed to preempt reservation for disk %s" % disk)
    return ret