hr, err := hash.NewReader(ctx, io.LimitReader(gr, part.Size), part.Size, "", "", part.ActualSize)
			if err != nil {
				return fmt.Errorf("rebalanceObject: hash.NewReader() %w", err)
			}
			pi, err := z.PutObjectPart(ctx, bucket, oi.Name, res.UploadID,
				part.Number,
				NewPutObjReader(hr),
				ObjectOptions{
					PreserveETag: part.ETag, // Preserve original ETag to ensure same metadata.
					IndexCB: func() []byte {

	md5Hex := getMD5Hash(fiveMBBytes)
	_, err = objLayer.PutObjectPart(ctx, "bucket1", "mpartObj1", res.UploadID, 1, mustGetPutObjReader(t, bytes.NewReader(fiveMBBytes), 5*humanize.MiByte, md5Hex, ""), opts)
	if err != nil {
		t.Fatal(err)
	}
	// PutObjectPart should succeed even if part already exists. ref: https://github.com/minio/minio/issues/1930

			hr, err := hash.NewReader(ctx, io.LimitReader(gr, part.Size), part.Size, "", "", part.ActualSize)
			if err != nil {
				return fmt.Errorf("decommissionObject: hash.NewReader() %w", err)
			}
			pi, err := z.PutObjectPart(ctx, bucket, objInfo.Name, res.UploadID,
				part.Number,
				NewPutObjReader(hr),
				ObjectOptions{
					PreserveETag: part.ETag, // Preserve original ETag to ensure same metadata.
					IndexCB: func() []byte {

		case "PutObjectPart":
			// Register PutObjectPart handler.
			bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(api.PutObjectPartHandler).Queries("partNumber", "{partNumber:.*}", "uploadId", "{uploadId:.*}")
		case "ListObjectParts":

	if err != nil {
		t.Fatal(err)
	}

	// Upload a part
	partData := bytes.Repeat([]byte("a"), 5*humanize.MiByte)
	md5Hex := getMD5Hash(partData)
	_, err = obj.PutObjectPart(ctx, bucket, object, res.UploadID, 1,
		mustGetPutObjReader(t, bytes.NewReader(partData), int64(len(partData)), md5Hex, ""),
		ObjectOptions{})
	if err != nil {
		t.Fatal(err)
	}

	if err != nil {
		t.Fatalf("Failed to create a multipart upload - %v", err)
	}

	var uploadedParts []CompletePart
	for _, partID := range []int{2, 1} {
		pInfo, err1 := objLayer.PutObjectPart(ctx, bucket, object, res.UploadID, partID, mustGetPutObjReader(t, bytes.NewReader(data), int64(len(data)), "", ""), opts)
		if err1 != nil {
			t.Fatalf("Failed to upload a part - %v", err1)
		}

	// Upload part1.
	fiveMBBytes := bytes.Repeat([]byte("a"), 5*humanize.MiByte)
	md5Writer := md5.New()
	md5Writer.Write(fiveMBBytes)
	etag1 := hex.EncodeToString(md5Writer.Sum(nil))
	sha256sum := ""
	_, err = obj.PutObjectPart(context.Background(), bucket, object, uploadID, 1, mustGetPutObjReader(t, bytes.NewReader(fiveMBBytes), int64(len(fiveMBBytes)), etag1, sha256sum), opts)
	if err != nil {
		// Failed to upload object part, abort.

	completedParts := CompleteMultipartUpload{}
	for i := 1; i <= 10; i++ {
		expectedETaghex := getMD5Hash(data)

		var calcPartInfo PartInfo
		calcPartInfo, err = obj.PutObjectPart(context.Background(), "bucket", "key", uploadID, i, mustGetPutObjReader(t, bytes.NewBuffer(data), int64(len(data)), expectedETaghex, ""), opts)
		if err != nil {
			t.Errorf("%s: <ERROR> %s", instanceType, err)
		}

		if err != nil {
			return err
		}
		pReader := NewPutObjReader(hr)
		opts.PreserveETag = ""
		pInfo, err = api.PutObjectPart(ctx, tgtBucket, tgtObject, res.UploadID, i+1, pReader, opts)
		if err != nil {
			return err
		}
		if pInfo.Size != objInfo.Size {
			return fmt.Errorf("Part size mismatch: got %d, want %d", pInfo.Size, objInfo.Size)

		hr, err := hash.NewReader(ctx, io.LimitReader(gr, partInfo.Size), partInfo.Size, "", "", partInfo.Size)
		if err != nil {
			return setRestoreHeaderFn(oi, err)
		}
		pInfo, err := er.PutObjectPart(ctx, bucket, object, res.UploadID, partInfo.Number, NewPutObjReader(hr), ObjectOptions{})
		if err != nil {
			return setRestoreHeaderFn(oi, err)
		}
		if pInfo.Size != partInfo.Size {