// Shuffle buckets to ensure total randomness of buckets, being scanned.
	// Otherwise same set of buckets get scanned across erasure sets always.
	// at any given point in time. This allows different buckets to be scanned
	// in different order per erasure set, this wider spread is needed when
	// there are lots of buckets with different order of objects in them.
	r := rand.New(rand.NewSource(time.Now().UnixNano()))

// ShardSize - returns actual shared size from erasure blockSize.
func (e ErasureInfo) ShardSize() int64 {
	return ceilFrac(e.BlockSize, int64(e.DataBlocks))
}

// IsValid - tells if erasure info fields are valid.
func (fi FileInfo) IsValid() bool {
	if fi.Deleted {
		// Delete marker has no data, no need to check
		// for erasure coding information
		return true
	}
	dataBlocks := fi.Erasure.DataBlocks

		fi.Size = 1 << 20
		metaArr := make([]FileInfo, N)
		parities := make([]int, N)
		for i := range N {
			fi.Erasure.Index = i + 1
			metaArr[i] = fi
			parities[i] = parity
			if i < agree {
				continue
			}
			metaArr[i].Erasure.Index = 0 // creates invalid fi on remaining drives
			parities[i] = -1             // invalid fi are assigned parity -1
		}
		res.metaArr = metaArr

	shardSize     int64
	shardFileSize int64
	buf           [][]byte
	readerToBuf   []int
	stashBuffer   []byte
}

// newParallelReader returns parallelReader.
func newParallelReader(readers []io.ReaderAt, e Erasure, offset, totalLength int64) *parallelReader {
	r2b := make([]int, len(readers))
	for i := range r2b {
		r2b[i] = i
	}
	bufs := make([][]byte, len(readers))
	shardSize := int(e.ShardSize())
	var b []byte

	for i, meta := range partsMetadata {
		if !meta.IsValid() {
			// Since for majority of the cases erasure.Index matches with erasure.Distribution we can
			// consider the offline disks as consistent.
			continue
		}
		if !meta.Deleted {
			if len(meta.Erasure.Distribution) != len(onlineDisks) {
				// Erasure distribution seems to have lesser
				// number of items than number of online disks.
				inconsistent++

)

// Tests isObjectDangling function
func TestIsObjectDangling(t *testing.T) {
	fi := newFileInfo("test-object", 2, 2)
	fi.Erasure.Index = 1

	ifi := newFileInfo("test-object", 2, 2)
	ifi.SetInlineData()
	ifi.Erasure.Index = 1

	testCases := []struct {
		name             string
		metaArr          []FileInfo
		errs             []error
		dataErrs         map[int][]int

		errs, latestMeta, filterDisksByETag, bucket, object, scanMode)

	var erasure Erasure
	if !latestMeta.Deleted && !latestMeta.IsRemote() {
		// Initialize erasure coding
		erasure, err = NewErasure(ctx, latestMeta.Erasure.DataBlocks,
			latestMeta.Erasure.ParityBlocks, latestMeta.Erasure.BlockSize)
		if err != nil {
			return result, err
		}
	}

		return 0, 0, err
	}

	if format.Erasure.This == offlineDiskUUID {
		return -1, -1, fmt.Errorf("DriveID: %s is offline", format.Erasure.This)
	}

	for i := 0; i < len(refFormat.Erasure.Sets); i++ {
		for j := 0; j < len(refFormat.Erasure.Sets[0]); j++ {
			if refFormat.Erasure.Sets[i][j] == format.Erasure.This {
				return i, j, nil
			}
		}
	}

	case size < fi.Erasure.BlockSize:
		// No need to allocate fully fi.Erasure.BlockSize buffer if the incoming data is smaller.
		buffer = make([]byte, size, 2*size+int64(fi.Erasure.ParityBlocks+fi.Erasure.DataBlocks-1))
	}

	if len(buffer) > int(fi.Erasure.BlockSize) {
		buffer = buffer[:fi.Erasure.BlockSize]
	}
	writers := make([]io.Writer, len(onlineDisks))
	for i, disk := range onlineDisks {
		if disk == nil {

	fi.DataDir = mustGetUUID()

	// Initialize erasure metadata.
	for index := range partsMetadata {
		partsMetadata[index] = fi
	}

	// Order disks according to erasure distribution
	var onlineDisks []StorageAPI
	onlineDisks, partsMetadata = shuffleDisksAndPartsMetadata(storageDisks, partsMetadata, fi)

	erasure, err := NewErasure(ctx, fi.Erasure.DataBlocks, fi.Erasure.ParityBlocks, fi.Erasure.BlockSize)
	if err != nil {