func (fi *FileInfo) TierFreeVersionID() string {
	return fi.Metadata[ReservedMetadataPrefixLower+tierFVID]
}

// SetTierFreeVersion sets fi as a free-version. This method is used by
// lower layers to indicate a free-version.
func (fi *FileInfo) SetTierFreeVersion() {
	if fi.Metadata == nil {
		fi.Metadata = make(map[string]string)
	}
	fi.Metadata[ReservedMetadataPrefixLower+tierFVMarker] = ""
}

		w.WriteHeader(499)
	default:
		w.WriteHeader(http.StatusForbidden)
	}
	w.Write([]byte(err.Error()))
}

// DefaultSkewTime - skew time is 15 minutes between minio peers.
const DefaultSkewTime = 15 * time.Minute

// Authenticates storage client's requests and validates for skewed time.
func storageServerRequestValidate(r *http.Request) error {