func optimalPartSize(objectSize int64) (partSize int64, err error) {
	// object size is '-1' set it to 5TiB.
	if objectSize == -1 {
		objectSize = maxMultipartPutObjectSize
	}

	// object size is larger than supported maximum.
	if objectSize > maxMultipartPutObjectSize {
		err = errors.New("entity too large")
		return
	}

	configuredPartSize := minPartSize
	// Use floats for part size for all calculations to avoid

	//
	// While this format is compatible with most tar readers,
	// the format has several limitations making it unsuitable for some usages.
	// Most notably, it cannot support sparse files, files larger than 8GiB,
	// filenames larger than 256 characters, and non-ASCII filenames.
	//
	// Reference:
	//	http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
	FormatUSTAR

	// Objects total count across all buckets
	ObjectsTotalCount uint64 `json:"objectsCount"`

	// Versions total count across all buckets
	VersionsTotalCount uint64 `json:"versionsCount"`

	// Delete markers total count across all buckets
	DeleteMarkersTotalCount uint64 `json:"deleteMarkersCount"`

	// Objects total size across all buckets
	ObjectsTotalSize uint64                           `json:"objectsTotalSize"`

var errSignatureMismatch = errors.New("Signature does not match")

// When upload object size is greater than 5G in a single PUT/POST operation.
var errDataTooLarge = errors.New("Object size larger than allowed limit")

// When upload object size is less than what was expected.
var errDataTooSmall = errors.New("Object size smaller than expected")

// errServerNotInitialized - server not initialized.

		return err
	}

	wk, err := workers.New(workerSize)
	if err != nil {
		// invalid worker size.
		return err
	}

	retryAttempts := ri.RetryAttempts
	ctx, cancel := context.WithCancel(ctx)

	results := make(chan ObjectInfo, 100)
	if err := api.Walk(ctx, r.Bucket, r.Prefix, results, WalkOptions{
		Marker: lastObject,
		Filter: selectObj,
	}); err != nil {
		cancel()

			prefix:       "photos/",
			marker:       "test",
			delimiter:    SlashSeparator,
			maxKeys:      100,
			encodingType: "gzip",
		},
		{
			values: url.Values{
				"prefix":        []string{"photos/"},
				"marker":        []string{"test"},
				"delimiter":     []string{SlashSeparator},
				"encoding-type": []string{"gzip"},
			},
			prefix:       "photos/",
			marker:       "test",

				return nil
			}
			gridConn.Store(gc)
			return gc
		},
	}
}

// Wrapper to restClient.Call to handle network errors, in case of network error the connection is marked disconnected
// permanently. The only way to restore the connection is at the xl-sets layer by xlsets.monitorAndConnectEndpoints()
// after verifying format.json

	fivs, err := getAllFileInfoVersions(xlMetaBuf, volume, path, allParts)
	if err != nil {
		return fivs, err
	}
	n := 0
	for _, fi := range fivs.Versions {
		// Filter our tier object delete marker
		if !fi.TierFreeVersion() {
			fivs.Versions[n] = fi
			n++
		} else {
			fivs.FreeVersions = append(fivs.FreeVersions, fi)
		}
	}
	fivs.Versions = fivs.Versions[:n]
	// Update numversions

// Special conditions required by MinIO server are as below
//   - delimiter if set should be equal to '/', otherwise the request is rejected.
//   - marker if set should have a common prefix with 'prefix' param, otherwise
//     the request is rejected.
func validateListObjectsArgs(prefix, marker, delimiter, encodingType string, maxKeys int) APIErrorCode {
	// Max keys cannot be negative.
	if maxKeys < 0 {
		return ErrInvalidMaxKeys
	}

	// and don't process the If-Modified-Since header.
	if objInfo.ModTime.IsZero() || objInfo.ModTime.Equal(time.Unix(0, 0)) {
		return false
	}

	// If top level is a delete marker proceed to upload.
	if objInfo.DeleteMarker {
		return false
	}

	// Headers to be set of object content is not going to be written to the client.
	writeHeaders := func() {
		// set common headers