code: public long snapshotCreationTime(String snapshotName)
      {
          for (File dir : dataPaths)
          {
              File snapshotDir = new File(dir, join(SNAPSHOT_SUBDIR, snapshotName));
              if (snapshotDir.exists())
                  return snapshotDir.lastModified();
          }
          throw new RuntimeException("Snapshot " + snapshotName + " doesn't exist");
      }
docs: The snapshot must exist