@Override
  public void markDiskDown() {
    throw new UnsupportedOperationException("No disk for CloudServiceReplica");
  }
Instantiate a {@link CloudServiceReplica}.
@param clusterMapConfig the {@link ClusterMapConfig} to use.
@param dataNode the {@link DataNode} to which this replica belongs to. This will usually be localhost, since that
                is where the client library runs from.
@param partition the {@link AmbryPartition} of which this is a replica.
@param capacityBytes the capacity in bytes for this replica.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/CloudServiceReplica.java