title: In Storm, how to migrate offsets to store in Kafka?
body: <p>I've been having all sorts of instabilities related to Kafka and offsets. Things like workers crashing on startup with exceptions related to invalidate offsets, and other things I don't understand.</p>
  
  <p>I read that it is recommended to migrate offsets to be stored in Kafka instead of Zookeeper. I found the below in the Kafka documentation:</p>
  
  <blockquote>
    <p>Migrating offsets from ZooKeeper to Kafka    Kafka consumers in
    earlier releases store their offsets by default in  ZooKeeper. It is
    possible to migrate these consumers to commit offsets  into Kafka by
    following these steps:    1. Set offsets.storage=kafka and
    dual.commit.enabled=true in your  consumer config.  2. Do a rolling
    bounce of your consumers and then verify  that your consumers are
    healthy.  3. Set dual.commit.enabled=false in your  consumer config.  4. Do
    a rolling bounce of your consumers and then verify that your consumers
    are healthy. </p>
    
    <p>A roll-back (i.e., migrating from  Kafka back to ZooKeeper) can also
    be performed using the above steps  if you set
    offsets.storage=zookeeper.</p>
  </blockquote>
  
  <p><a href="http://kafka.apache.org/documentation.html#offsetmigration" rel="nofollow">http://kafka.apache.org/documentation.html#offsetmigration</a></p>
  
  <p>But, again, I don't understand what this is instructing me to do. I don't see anywhere in my topology config where I configure where offsets are stored. Is it buried in the cluster yaml? </p>
  
  <p>Any advice on if storing offsets in Kafka, rather than Zookeeper, is a good idea? And how I can perform this change?</p>