@Override
  public String toString() {
    try {
      return toJSONObject().toString(2);
    } catch (JSONException e) {
      logger.error("JSONException caught in toString: {}", e.getCause());
    }
    return null;
  }
Finds Disk by hostname, port, and mount path.

@param hostname of datanode
@param port of datanode
@param mountPath of disk
@return Disk or null if not found.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HardwareLayout.java