private long calculateRawCapacityInBytes() {
    long capacityInBytes = 0;
    for (Datacenter datacenter : datacenters) {
      capacityInBytes += datacenter.getRawCapacityInBytes();
    }
    return capacityInBytes;
  }
An Ambry hardwareLayout consists of a set of {@link Datacenter}s.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HardwareLayout.java