title: Why kafka cluster did error "Number of alive brokers '0' does not meet the required replication factor"?
body: <p>I have 2 kafka brokers and 1 zookeeper. Brokers config: server.properties file:
  1 broker:</p>
  
  <pre><code>auto.create.topics.enable=true
  broker.id=1
  delete.topic.enable=true
  group.initial.rebalance.delay.ms=0
  listeners=PLAINTEXT://5.1.2.3:9092
  log.dirs=/opt/kafka_2.12-2.1.0/logs
  log.retention.check.interval.ms=300000
  log.retention.hours=168
  log.segment.bytes=1073741824
  max.message.bytes=105906176
  message.max.bytes=105906176
  num.io.threads=8
  num.network.threads=3
  num.partitions=10
  num.recovery.threads.per.data.dir=1
  offsets.topic.replication.factor=1
  replica.fetch.max.bytes=105906176
  socket.receive.buffer.bytes=102400
  socket.request.max.bytes=105906176
  socket.send.buffer.bytes=102400
  transaction.state.log.min.isr=1
  transaction.state.log.replication.factor=1
  zookeeper.connect=5.1.3.6:2181
  zookeeper.connection.timeout.ms=6000
  </code></pre>
  
  <p>2 broker:</p>
  
  <pre><code>auto.create.topics.enable=true
  broker.id=2
  delete.topic.enable=true
  group.initial.rebalance.delay.ms=0
  listeners=PLAINTEXT://18.4.6.6:9092
  log.dirs=/opt/kafka_2.12-2.1.0/logs
  log.retention.check.interval.ms=300000
  log.retention.hours=168
  log.segment.bytes=1073741824
  max.message.bytes=105906176
  message.max.bytes=105906176
  num.io.threads=8
  num.network.threads=3
  num.partitions=10
  num.recovery.threads.per.data.dir=1
  offsets.topic.replication.factor=1
  replica.fetch.max.bytes=105906176
  socket.receive.buffer.bytes=102400
  socket.request.max.bytes=105906176
  socket.send.buffer.bytes=102400
  transaction.state.log.min.isr=1
  transaction.state.log.replication.factor=1
  zookeeper.connect=5.1.3.6:2181
  zookeeper.connection.timeout.ms=6000
  </code></pre>
  
  <p>if i ask zookeeper like this: </p>
  
  <blockquote>
    <p>echo dump | nc zook_IP 2181</p>
  </blockquote>
  
  <p>i got:</p>
  
  <pre><code>SessionTracker dump:
  Session Sets (3):
  0 expire at Sun Jan 04 03:40:27 MSK 1970:
  1 expire at Sun Jan 04 03:40:30 MSK 1970:
          0x1000bef9152000b
  1 expire at Sun Jan 04 03:40:33 MSK 1970:
          0x1000147d4b40003
  ephemeral nodes dump:
  Sessions with Ephemerals (2):
  0x1000147d4b40003:
          /controller
          /brokers/ids/2
  0x1000bef9152000b:
          /brokers/ids/1
  </code></pre>
  
  <p>looke fine, but not works :(. Zookeeper see 2 brokers, but in first kafka broker we have error:</p>
  
  <pre><code> ERROR [KafkaApi-1] Number of alive brokers '0' does not meet the required replication factor '1' for the offsets topic (configured via 'offsets.topic.replication.factor'). This error can be ignored if the cluster is starting up and not all brokers are up yet. (kafka.server.KafkaApis)
  </code></pre>
  
  <p>also we use kafka_exporter for prometheus, and he log this error:</p>
  
  <pre><code>Cannot get oldest offset of topic Some.TOPIC partition 9: kafka server: Request was for a topic or partition that does not exist on this broker." source="kafka_exporter.go:296
  </code></pre>
  
  <p>pls help ! were i mistake in config ?</p>