private static void createPersistentReplicateRegion(GemFireCache cache, String regionName,
      File diskStore) {
    DiskStore store = cache.findDiskStore("store");
    if (store == null) {
      DiskStoreFactory factory = cache.createDiskStoreFactory();
      factory.setMaxOplogSize(1L);
      factory.setDiskDirs(new File[] {diskStore.getAbsoluteFile()});
      factory.create("store");
    }
    RegionFactory rf = ((GemFireCacheImpl) cache).createRegionFactory();
    rf.setDiskStoreName("store");
    rf.setDataPolicy(DataPolicy.PERSISTENT_REPLICATE);
    rf.create(regionName);
  }
This test starts up multiple servers from the current code base and multiple servers from the
old version and executes puts and gets on a new server and old server and verifies that the
results are present. Note that the puts have overlapping region keys just to test new puts and
replaces
geode-core/src/upgradeTest/java/org/apache/geode/internal/cache/rollingupgrade/RollingUpgrade2DUnitTestBase.java