@Override
  public int getPort() {
    return portNum;
  }
An extension of {@link DataNodeId} to be used within the {@link StaticClusterManager}.

DataNode is uniquely identified by its hostname and port. A DataNode is in a {@link Datacenter}. A DataNode has zero
or more {@link Disk}s.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/DataNode.java