public static void modifyDiskStore(List args) {
    String diskStoreName = (String) args.get(0);
    List dirList = args.subList(1, args.size());
    File[] dirs = new File[dirList.size()];
    Iterator it = dirList.iterator();
    int idx = 0;
    while (it.hasNext()) {
      dirs[idx] = new File((String) it.next());
      idx++;
    }
    try {
      if (lruOption != null || lruActionOption != null || lruLimitOption != null
          || concurrencyLevelOption != null || initialCapacityOption != null
          || loadFactorOption != null || compressorClassNameOption != null
          || statisticsEnabledOption != null) {
        if (regionOption == null) {
          throw new IllegalArgumentException("modify-disk-store requires -region=<regionName>");
        }
        if (remove) {
          throw new IllegalArgumentException(
              "the -remove option can not be used with the other modify options.");
        }
        DiskStoreImpl.modifyRegion(diskStoreName, dirs, regionOption, lruOption, lruActionOption,
            lruLimitOption, concurrencyLevelOption, initialCapacityOption, loadFactorOption,
            compressorClassNameOption, statisticsEnabledOption, null/* offHeap */, true);
        System.out.println("The region " + regionOption
            + " was successfully modified in the disk store " + diskStoreName);
      } else if (remove) {
        if (regionOption == null) {
          throw new IllegalArgumentException("modify-disk-store requires -region=<regionName>");
        }
        DiskStoreImpl.destroyRegion(diskStoreName, dirs, regionOption);
        System.out.println("The region " + regionOption
            + " was successfully removed from the disk store " + diskStoreName);
      } else {
        DiskStoreImpl.dumpInfo(System.out, diskStoreName, dirs, regionOption, null);
        if (regionOption == null) {
          System.out.println("Please specify -region=<regionName> and a modify option.");
        } else {
          System.out.println("Please specify a modify option.");
        }
      }
    } catch (Exception ex) {
      throw new GemFireIOException(" disk-store=" + diskStoreName + ": " + 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