public static Region<Object, Object> getSyncPersistOnlyRegion(Cache cache,
      DiskRegionProperties diskRegionProperties, Scope regionScope) {
    if (diskRegionProperties == null) {
      diskRegionProperties = new DiskRegionProperties();
    }
    diskRegionProperties.setPersistBackup(true);
    diskRegionProperties.setSynchronous(true);
    return getRegion(cache, diskRegionProperties, regionScope);

  }
A testing helper factory to get a disk region with the desired configuration
geode-junit/src/main/java/org/apache/geode/internal/cache/DiskRegionHelperFactory.java