title: Kafka Partitions Reassignment Performance Impact
body: <p>I have a Kafka production cluster with 5 nodes and about 500 topics. I need to expand my cluster to add 2 new nodes and since, Kafka does not provide automatic data repartitioning, I am looking to run <code>kafka-reassign-partitions.sh</code> shipped along with Kafka distribution to rebalance all my topics in the overall 7 nodes in the cluster now.</p>
  
  <p>Since I already have a large amount of production data in my cluster,</p>
  
  <ol>
  <li>Will running this script block any concurrent writes to my Kafka topics ?</li>
  <li>Will running this script slow down my cluster/producers/consumers ?</li>
  <li>How can I stop this script while it is in-progress in case my cluster starts misbehaving during this script's execution ?</li>
  </ol>
  
  <p>I am currently using Kafka <code>v0.8.2.0</code> with multiple producers and multiple consumers.</p>