public List<Integer> getDataRegionIds() {
    List<Integer> dataRegionIds = new ArrayList<>();
    getPartitionManager()
        .getDataRegionIds(
            new ArrayList<>(quotaInfo.getSpaceQuotaLimit().keySet()), dataRegionIdMap);
    dataRegionIdMap.values().forEach(dataRegionIds::addAll);
    return dataRegionIds;
  }
If the new quota is smaller than the quota already used, the setting fails.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/ClusterQuotaManager.java