int getNumberOfPartitionsInResource(String resource) {
    String dcName = clusterMapConfig.clusterMapDatacenterName;
    String tag = dcToResourceNameToTag.get(dcName).get(resource);
    return dcToTagToResourceProperty.get(dcName).get(tag).numPartitions;
  }
Callback method when this data node is becoming SEMI AUTO from FULL AUTO.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HelixClusterManager.java