@Test
  public void testEntryUpdateInASyncPersistOnlyForIOExceptionCase() throws Exception {
    DiskRegionProperties diskRegionProperties = new DiskRegionProperties();
    diskRegionProperties.setRegionName(regionName);
    diskRegionProperties.setOverflow(true);
    diskRegionProperties.setRolling(false);
    diskRegionProperties.setBytesThreshold(48);
    diskRegionProperties.setDiskDirs(diskDirs);
    diskRegionProperties.setPersistBackup(true);

    DiskStoreFactory diskStoreFactory = toDiskStoreFactory(diskRegionProperties);

    createDiskStoreWithSizeInBytes(diskStoreName, diskStoreFactory);

    Region<Object, Object> region =
        createRegion(regionName, diskStoreName, true, false, false, true, DEFAULT_ENTRIES_MAXIMUM);

    closeOplogFileChannel(region);

    region.create("key1", new byte[16]);
    region.create("key2", new byte[16]);

    DiskRegion diskRegion = getDiskRegion(region);
    diskRegion.flushForTesting();

    verifyClosedDueToDiskAccessException(region);
  }
If IOException occurs while updating an entry in an Asynch mode, DiskAccessException should
occur & region should be destroyed
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/DiskRegionJUnitTest.java