doneCh := make(chan error, 1)
	defer xioutil.SafeClose(doneCh)

	// Save rebalance.bin periodically.
	go func() {
		// Update rebalance.bin periodically once every 5-10s, chosen randomly
		// to avoid multiple pool leaders herding to update around the same
		// time.
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		randSleepFor := func() time.Duration {