testReadFrom{fileOps{
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),

			blockLength = e.blockSize - blockOffset
		case block == endBlock:
			blockOffset = 0
			blockLength = (offset + length) % e.blockSize
		default:
			blockOffset = 0
			blockLength = e.blockSize
		}
		if blockLength == 0 {
			break
		}

		var err error
		bufs, err = reader.Read(bufs)
		if len(bufs) > 0 {
			// Set only if there are be enough data for reconstruction.

	DataBlocks int `json:"data"`
	// ParityBlocks is the number of parity blocks for erasure-coding
	ParityBlocks int `json:"parity"`
	// BlockSize is the size of one erasure-coded block
	BlockSize int64 `json:"blockSize"`
	// Index is the index of the current disk
	Index int `json:"index"`
	// Distribution is the distribution of the data and parity blocks
	Distribution []int `json:"distribution"`

		case "ParityBlocks":
			z.ParityBlocks, err = dc.ReadInt()
			if err != nil {
				err = msgp.WrapError(err, "ParityBlocks")
				return
			}
		case "BlockSize":
			z.BlockSize, err = dc.ReadInt64()
			if err != nil {
				err = msgp.WrapError(err, "BlockSize")
				return
			}
		case "Index":
			z.Index, err = dc.ReadInt()
			if err != nil {
				err = msgp.WrapError(err, "Index")
				return
			}

		// max requests per node is calculated as
		// total_ram / ram_per_request
		blockSize := xioutil.LargeBlock + xioutil.SmallBlock
		if legacy {
			// ram_per_request is (1MiB+32KiB) * driveCount \
			//    + 2 * 10MiB (default erasure block size v1) + 2 * 1MiB (default erasure block size v2)
			apiRequestsMaxPerNode = int(maxMem / uint64(maxSetDrives*blockSize+int(blockSizeV1*2+blockSizeV2*2)))
		} else {

	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 {

func (fi FileInfo) shardSize() int64 {
	return ceilFrac(fi.Erasure.BlockSize, int64(fi.Erasure.DataBlocks))
}

// ShardFileSize - returns final erasure size from original size.
func (fi FileInfo) ShardFileSize(totalLength int64) int64 {
	if totalLength == 0 {
		return 0
	}
	if totalLength == -1 {
		return -1
	}
	numShards := totalLength / fi.Erasure.BlockSize
	lastBlockSize := totalLength % fi.Erasure.BlockSize

	if totalLength == -1 {
		return -1
	}
	numShards := totalLength / e.BlockSize
	lastBlockSize := totalLength % e.BlockSize
	lastShardSize := ceilFrac(lastBlockSize, int64(e.DataBlocks))
	return numShards*e.ShardSize() + lastShardSize
}

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

		Size:             0,
		Mode:             0,
		Metadata:         nil,
		Parts:            nil,
		Erasure: ErasureInfo{
			Algorithm:    ReedSolomon.String(),
			DataBlocks:   4,
			ParityBlocks: 2,
			BlockSize:    10000,
			Index:        1,
			Distribution: []int{1, 2, 3, 4, 5, 6, 7, 8},
			Checksums: []ChecksumInfo{{
				PartNumber: 1,
				Algorithm:  HighwayHash256S,
				Hash:       nil,
			}},
		},

	case size == 0:
		buffer = make([]byte, 1) // Allocate at least a byte to reach EOF
	case size >= fi.Erasure.BlockSize:
		buffer = globalBytePoolCap.Load().Get()
		defer globalBytePoolCap.Load().Put(buffer)
	case size < fi.Erasure.BlockSize:
		// No need to allocate fully blockSizeV1 buffer if the incoming data is smaller.
		buffer = make([]byte, size, 2*size+int64(fi.Erasure.ParityBlocks+fi.Erasure.DataBlocks-1))
	}