private String createDiskStoreAndGetName() {
    Cache cache = getCache();
    File[] diskDirs = new File[1];
    diskDirs[0] = new File("diskRegionDirs/" + getClass().getCanonicalName());
    diskDirs[0].mkdirs();
    DiskStoreFactory diskStoreFactory = cache.createDiskStoreFactory();
    diskStoreFactory.setDiskDirs(diskDirs);
    String diskStoreName = getClass().getName();
    diskStoreFactory.create(diskStoreName);
    return diskStoreName;
  }
Test for transactional operations on overflowed data
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/eviction/TransactionsWithOverflowTest.java