public static void upgradeDiskStore(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 {
      DiskStoreImpl.offlineCompact(diskStoreName, dirs, true, maxOplogSize);
    } catch (Exception ex) {
      throw new GemFireIOException(" disk-store=" + diskStoreName + ": " + ex, ex);
    }
  }
Tails the end of the locator's log file

@since GemFire 4.0
geode-core/src/main/java/org/apache/geode/internal/SystemAdmin.java