title: Restoration of outdated config server
body: <p>We have 1 test mongodb cluster that includes</p>
  
  <ul>
  <li><p>1 mongos servers</p></li>
  <li><p>3 config servers</p></li>
  <li><p>6 shards</p></li>
  </ul>
  
  <p><strong>Q1.</strong> We have tried to restore a outdated config server backup.  We can only find that the config.chunks have less records than before but we can query and insert/update data in the mongodb.  What will be the worst result if we use an outdated config server backup ?</p>
  
  <p><strong>Q2.</strong> Is there any tools that can re-build the loss records in config server with the existing data in each shard ?</p>