code: protected void doBackup(File backupFile) throws BackupException
     {
        ZipObjectWriter out = null;
        try
        {
           out = new ZipObjectWriter(PrivilegedFileHelper.zipOutputStream(backupFile));
           quotaPersister.backupWorkspaceData(rName, wsName, out);
        }
        catch (IOException e)
        {
           throw new BackupException(e);
        }
        finally
        {
           if (out != null)
           {
              try
              {
                 out.close();
              }
              catch (IOException e)
              {
                 LOG.error("Can't close output stream", e);
              }
           }
        }
     }
docs: Backups data to define file.