// 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()))

	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 {

	formatV2.Format = formatBackendErasure
	formatV2.Erasure.Version = formatErasureVersionV2
	formatV2.Erasure.DistributionAlgo = formatErasureVersionV2DistributionAlgoV1
	formatV2.Erasure.This = formatV1.Erasure.Disk
	formatV2.Erasure.Sets = make([][]string, 1)
	formatV2.Erasure.Sets[0] = make([]string, len(formatV1.Erasure.JBOD))
	copy(formatV2.Erasure.Sets[0], formatV1.Erasure.JBOD)

	return json.Marshal(formatV2)
}

	return fmt.Errorf("%w (offline-disks=%d/%d)", writeErr, countErrs(p.errs, errDiskNotFound), len(p.writers))
}

// Encode reads from the reader, erasure-encodes the data and writes to the writers.
func (e *Erasure) Encode(ctx context.Context, src io.Reader, writers []io.Writer, buf []byte, quorum int) (total int64, err error) {
	writer := &parallelWriter{
		writers:     writers,
		writeQuorum: quorum,

erasure-code.svg...

	for i, test := range erasureEncodeDecodeTests {
		buffer := make([]byte, len(data), 2*len(data))
		copy(buffer, data)

		erasure, err := NewErasure(context.Background(), test.dataBlocks, test.parityBlocks, blockSizeV2)
		if err != nil {
			t.Fatalf("Test %d: failed to create erasure: %v", i, err)
		}
		encoded, err := erasure.EncodeData(context.Background(), buffer)
		if err != nil {
			t.Fatalf("Test %d: failed to encode data: %v", i, err)
		}

	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 {

erasure-code.jpg...

// 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

	"github.com/minio/minio/internal/logger"
)

// Erasure - erasure encoding details.
type Erasure struct {
	encoder                  func() reedsolomon.Encoder
	dataBlocks, parityBlocks int
	blockSize                int64
}

// NewErasure creates a new ErasureStorage.
func NewErasure(ctx context.Context, dataBlocks, parityBlocks int, blockSize int64) (e Erasure, err error) {
	// Check the parameters for sanity now.