private void cmnEndDestroyRegion(DiskRegionView dr) {
    // Figure out how may other records this freed up.

    if (dr != null) {
      if (dr.getClearOplogEntryId() != DiskStoreImpl.INVALID_ID) {
        // one for the clear record
        ifLiveRecordCount--;
      }
      // one for each online member
      ifLiveRecordCount -= dr.getOnlineMembers().size();
      // one for each offline member
      ifLiveRecordCount -= dr.getOfflineMembers().size();
      // one for each equal member
      ifLiveRecordCount -= dr.getOfflineAndEqualMembers().size();



      // one for the CREATE_REGION
      ifLiveRecordCount--;

      // one for the regions memberId
      if (dr.getMyPersistentID() != null) {
        ifLiveRecordCount--;
      }

      liveRegions--;
      drMap.remove(dr.getId());
      drMapByName.remove(dr.getName());
      parent.rmById(dr.getId());

      dr.markEndDestroyRegion();
    } else {
      if (logger.isTraceEnabled(LogMarker.PERSIST_RECOVERY_VERBOSE)) {
        logger.trace(LogMarker.PERSIST_RECOVERY_VERBOSE, "bad disk region id!");
      } else {
        throw new IllegalStateException("bad disk region id");
      }
    }
  }
Maximum number of bytes used to encode a DiskRegion id.
geode-core/src/main/java/org/apache/geode/internal/cache/DiskInitFile.java