public static void exportDiskStore(ArrayList<String> args, String outputDir) {
    File out = outputDir == null ? new File(".") : new File(outputDir);
    if (!out.exists()) {
      out.mkdirs();
    }

    String dsName = args.get(0);
    File[] dirs = argsToFile(args.subList(1, args.size()));

    try {
      DiskStoreImpl.exportOfflineSnapshot(dsName, dirs, out);
    } catch (Exception ex) {
      throw new GemFireIOException(" disk-store=" + dsName + ": " + ex, ex);
    }
  }
this is a test hook to allow us to drive SystemAdmin functions without invoking main(), which
can call System.exit().
geode-core/src/main/java/org/apache/geode/internal/SystemAdmin.java