private void validateInitialOverflowStats() {
    assertThat(vm0.invoke(() -> ((PartitionedRegion) (cacheRule.getCache().getRegion(REGION_NAME)))
        .getDiskRegionStats().getNumEntriesInVM())).isEqualTo(LRU_ENTRY_COUNT);
    assertThat(vm0.invoke(() -> ((PartitionedRegion) (cacheRule.getCache().getRegion(REGION_NAME)))
        .getDiskRegionStats().getNumOverflowOnDisk()))
            .isEqualTo(ENTRIES_IN_REGION - LRU_ENTRY_COUNT);
  }
Do validation the initial region for the member containing all the data
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/partitioned/BucketRebalanceStatRegressionTest.java