title: kafka + ReplicaFetcherThread & Error for partitions
body: <p>we have Kafka cluster with 11 brokers on Linux machines</p>
  <p>brokers IDS are</p>
  <pre><code>1001
  1002
  .
  .
  .
  1011
  </code></pre>
  <p>we have topics as  - my_first_car , with <code>300 partitions</code> , and this topic configured with replication <code>factor = 3</code></p>
  <p>we notice from server.log the following <code>ERRORS</code>  ( from the first broker - 1001 )</p>
  <pre><code>[2022-03-02 07:15:52,450] ERROR [ReplicaFetcherThread-0-1005], Error for partition [my_first_car1,57] to broker 1005:org.apache.kafka.common.errors.UnknownServerException: The server experienced an unexpected error when processing the request (kafka.server.ReplicaFetcherThread)
  
  
  [2022-03-02 07:15:52,450] ERROR [ReplicaFetcherThread-0-1005], Error for partition [my_first_car2,37] to broker 1005:org.apache.kafka.common.errors.UnknownServerException: The server experienced an unexpected error when processing the request (kafka.server.ReplicaFetcherThread)
  </code></pre>
  <p><strong>what we can learn from ERRORS above?</strong></p>
  <p><code>server.log</code> on all Kafka's is filled with that <code>ERRORS</code></p>
  <p>is that <code>ERROR</code> could be related to network problem or else?</p>
  <p>need to mention that all <code>kafka</code> services are up ,</p>
  <p>and we set the correct Kafka heap size memory</p>
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  <p>as I know - UnknownTopicOrPartitionException</p>
  <p>Literally: topic or partition does not exist.
  For example: topic has a total of 3 partitions, p0, p1, p2, and if you specify to write data to p3, this exception will be reported</p>
  <p>but in my case the topics partitions are exists</p>