DiskStoreAttributesCreation initializePdxDiskStore(InternalCache cache) {
    // Create the disk store used by the pdx registry first.
    // If it is using the default disk store we need to create it now.
    // If the cache has a pool then no need to create disk store.
    DiskStoreAttributesCreation pdxRegDSC = null;
    if (TypeRegistry.mayNeedDiskStore(cache)) {
      String pdxRegDsName = cache.getPdxDiskStore();
      if (pdxRegDsName == null) {
        pdxRegDsName = DiskStoreFactory.DEFAULT_DISK_STORE_NAME;
      }
      pdxRegDSC = (DiskStoreAttributesCreation) diskStores.get(pdxRegDsName);
      if (pdxRegDSC == null) {
        if (pdxRegDsName.equals(DiskStoreFactory.DEFAULT_DISK_STORE_NAME)) {
          // need to create default disk store
          cache.getOrCreateDefaultDiskStore();
        }
      } else {
        createDiskStore(pdxRegDSC, cache);
      }
    }
    return pdxRegDSC;
  }
Returns a description of the disk store used by the pdx registry.
geode-core/src/main/java/org/apache/geode/internal/cache/xmlcache/CacheCreation.java