return nil, &fs.PathError{Op: "ReadDir", Path: dir, Err: fs.ErrNotExist}
	}
	diskfis, err := readDir(dir)
	if err != nil && !os.IsNotExist(err) && !errors.Is(err, errNotDir) {
		return nil, err
	}

	// Stat files in overlay to make composite list of fileinfos
	files := make(map[string]fs.FileInfo)
	for _, f := range diskfis {
		files[f.Name()] = f
	}
	for name, to := range dirNode.children {
		switch {

if (disks not recognized) // Always error.

// Specific checks.
if (all disks online)
  if (all disks return format.json)
     if (jbod consistent)
        if (all disks recognized)
          return
  else
     if (all disks return format.json not found)
        return error
     else (some disks return format.json not found)
        (heal format)
        return
     fi
   fi
else

	}
	h.disk = disk
	h.ID = diskID
	h.mu = &sync.RWMutex{}
	return &h, nil
}

// newHealingTracker will create a new healing tracker for the disk.
func newHealingTracker() *healingTracker {
	return &healingTracker{
		mu: &sync.RWMutex{},
	}
}

func initHealingTracker(disk StorageAPI, healID string) *healingTracker {
	h := newHealingTracker()
	diskID, _ := disk.GetDiskID()

	// otherwise, in second phase, rescan scsi bus and search again, return with any findings
	for true {
		for _, diskID := range diskIDs {
			if len(wwns) != 0 {
				disk, dm = findDisk(diskID, lun, io, b.deviceUtil)
			} else {
				disk, dm = findDiskWWIDs(diskID, io, b.deviceUtil)
			}
			// if multipath device is found, break
			if dm != "" {
				break
			}
		}
		// if a dm is found, exit loop

	// healing tracker is always for local disks.
	return nil
}

func (client *storageRESTClient) NSScanner(ctx context.Context, cache dataUsageCache, updates chan<- dataUsageEntry, scanMode madmin.HealScanMode, _ func() bool) (dataUsageCache, error) {
	defer xioutil.SafeClose(updates)

	st, err := storageNSScannerRPC.Call(ctx, client.gridConn, &nsScannerOptions{
		DiskID:   *client.diskID.Load(),
		ScanMode: int(scanMode),

// listOnlineDisks - returns
// - a slice of disks where disk having 'older' xl.meta (or nothing)
// are set to nil.
// - latest (in time) of the maximally occurring modTime(s), which has at least quorum occurrences.
func listOnlineDisks(disks []StorageAPI, partsMetadata []FileInfo, errs []error, quorum int) (onlineDisks []StorageAPI, modTime time.Time, etag string) {
	onlineDisks = make([]StorageAPI, len(disks))

func (client *storageRESTClient) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) error {
	// Ensure remote has the same disk ID.
	opts.DiskID = *client.diskID.Load()
	b, err := opts.MarshalMsg(grid.GetByteBuffer()[:0])
	if err != nil {
		return toStorageErr(err)
	}

	st, err := client.gridConn.NewStream(ctx, grid.HandlerWalkDir, b)
	if err != nil {

		This    string `json:"this"`    // This field carries assigned disk uuid.
		// Sets field carries the input disk order generated the first
		// time when fresh disks were supplied, it is a two dimensional
		// array second dimension represents list of disks used per set.
		Sets [][]string `json:"sets"`
		// Distribution algorithm represents the hashing algorithm
		// to pick the right set index for an object.

}

// shuffleDisks - shuffle input disks slice depending on the
// erasure distribution. Return shuffled slice of disks with
// their expected distribution.
func shuffleDisks(disks []StorageAPI, distribution []int) (shuffledDisks []StorageAPI) {
	if distribution == nil {
		return disks
	}
	shuffledDisks = make([]StorageAPI, len(disks))
	// Shuffle disks for expected distribution.
	for index := range disks {

	// upto GOMAXPROCS if GOMAXPROCS is < len(disks)
	maxProcs := runtime.GOMAXPROCS(0)
	if maxProcs < len(disks) {
		disks = disks[:maxProcs]
	}

	// Start one scanner per disk
	var wg sync.WaitGroup
	wg.Add(len(disks))

	for i := range disks {
		go func(i int) {
			defer wg.Done()
			disk := disks[i]

			for bucket := range bucketCh {
				select {