private long countDisks() {
    return hardwareLayout.getDiskCount();
  }
Metrics for the {@link StaticClusterManager}
@param hardwareLayout The {@link HardwareLayout} associated with the {@link StaticClusterManager}
@param partitionLayout The {@link PartitionLayout} associated with the {@link StaticClusterManager}
@param registry The {@link MetricRegistry} associated with the {@link StaticClusterManager}
ambry-clustermap/src/main/java/com/github/ambry/clustermap/ClusterMapMetrics.java