code: public void clean() throws BackupException
     {
        LOG.info("Start to clean old data from the storage");
        try
        {
           SecurityHelper.doPrivilegedIOExceptionAction(new PrivilegedExceptionAction<Void>()
           {
              public Void run() throws IOException
              {
                 for (int i = 0; i < dataDirs.size(); i++)
                 {
                    File dataDir = dataDirs.get(i);
  
                    File tmpDir = new File(tempDir, PREFIX + IdGenerator.generate());
                    tmpDir.mkdirs();
                    tmpDirs.add(tmpDir);
  
                    if (dataDir.exists())
                    {
                       DirectoryHelper.copyDirectory(dataDir, tmpDir);
                       DirectoryHelper.removeDirectory(dataDir);
                    }
                 }
  
                 return null;
              }
           });
        }
        catch (IOException e)
        {
           throw new BackupException(e);
        }
     }
docs: {@inheritDoc}