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https://issues.apache.org/jira/browse/KAFKA-1555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14144378#comment-14144378
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Joe Stein commented on KAFKA-1555:
----------------------------------
[~gwenshap] patch applied, tests passed however; I ran with 3 brokers all new
code and didn't get the expected results
{code}
Topic:testDefault PartitionCount:4 ReplicationFactor:3 Configs:
Topic: testDefault Partition: 0 Leader: 1 Replicas: 1,2,3
Isr: 1
Topic: testDefault Partition: 1 Leader: 1 Replicas: 2,3,1
Isr: 1
Topic: testDefault Partition: 2 Leader: 1 Replicas: 3,1,2
Isr: 1
Topic: testDefault Partition: 3 Leader: 1 Replicas: 1,3,2
Isr: 1
Topic:testNew PartitionCount:4 ReplicationFactor:3
Configs:min.insync.replicas=2
Topic: testNew Partition: 0 Leader: 1 Replicas: 2,1,3 Isr: 1
Topic: testNew Partition: 1 Leader: 1 Replicas: 3,2,1 Isr: 1
Topic: testNew Partition: 2 Leader: 1 Replicas: 1,3,2 Isr: 1
Topic: testNew Partition: 3 Leader: 1 Replicas: 2,3,1 Isr: 1
{code}
I am still able to produce to topic testNew (though I shouldn't be able too
since 2 brokers are down and only 1 is up with min.isr=2)
I got proper exceptions trying to create invalid values for the config
{code}
root@precise64:/opt/apache/kafka# bin/kafka-topics.sh --zookeeper
localhost:2181 --create --topic testNewA --partitions 4 --replication-factor 3
--config min.insync.replicas=-1
Error while executing topic command Wrong value -1 of min.insync.replicas in
Topic configuration; Valid values are at least 1
kafka.common.InvalidConfigException: Wrong value -1 of min.insync.replicas in
Topic configuration; Valid values are at least 1
at kafka.log.LogConfig$.validateMinInSyncReplicas(LogConfig.scala:191)
at kafka.log.LogConfig$.validate(LogConfig.scala:179)
at
kafka.admin.TopicCommand$.parseTopicConfigsToBeAdded(TopicCommand.scala:204)
at kafka.admin.TopicCommand$.createTopic(TopicCommand.scala:84)
at kafka.admin.TopicCommand$.main(TopicCommand.scala:54)
at kafka.admin.TopicCommand.main(TopicCommand.scala)
root@precise64:/opt/apache/kafka# bin/kafka-topics.sh --zookeeper
localhost:2181 --create --topic testNewA --partitions 4 --replication-factor 3
--config min.insync.replicas=4
Error while executing topic command replication factor: 3 larger than available
brokers: 1
kafka.admin.AdminOperationException: replication factor: 3 larger than
available brokers: 1
at kafka.admin.AdminUtils$.assignReplicasToBrokers(AdminUtils.scala:70)
at kafka.admin.AdminUtils$.createTopic(AdminUtils.scala:171)
at kafka.admin.TopicCommand$.createTopic(TopicCommand.scala:92)
at kafka.admin.TopicCommand$.main(TopicCommand.scala:54)
at kafka.admin.TopicCommand.main(TopicCommand.scala)
{code}
> provide strong consistency with reasonable availability
> -------------------------------------------------------
>
> Key: KAFKA-1555
> URL: https://issues.apache.org/jira/browse/KAFKA-1555
> Project: Kafka
> Issue Type: Improvement
> Components: controller
> Affects Versions: 0.8.1.1
> Reporter: Jiang Wu
> Assignee: Gwen Shapira
> Fix For: 0.8.2
>
> Attachments: KAFKA-1555.0.patch, KAFKA-1555.1.patch,
> KAFKA-1555.2.patch, KAFKA-1555.3.patch
>
>
> In a mission critical application, we expect a kafka cluster with 3 brokers
> can satisfy two requirements:
> 1. When 1 broker is down, no message loss or service blocking happens.
> 2. In worse cases such as two brokers are down, service can be blocked, but
> no message loss happens.
> We found that current kafka versoin (0.8.1.1) cannot achieve the requirements
> due to its three behaviors:
> 1. when choosing a new leader from 2 followers in ISR, the one with less
> messages may be chosen as the leader.
> 2. even when replica.lag.max.messages=0, a follower can stay in ISR when it
> has less messages than the leader.
> 3. ISR can contains only 1 broker, therefore acknowledged messages may be
> stored in only 1 broker.
> The following is an analytical proof.
> We consider a cluster with 3 brokers and a topic with 3 replicas, and assume
> that at the beginning, all 3 replicas, leader A, followers B and C, are in
> sync, i.e., they have the same messages and are all in ISR.
> According to the value of request.required.acks (acks for short), there are
> the following cases.
> 1. acks=0, 1, 3. Obviously these settings do not satisfy the requirement.
> 2. acks=2. Producer sends a message m. It's acknowledged by A and B. At this
> time, although C hasn't received m, C is still in ISR. If A is killed, C can
> be elected as the new leader, and consumers will miss m.
> 3. acks=-1. B and C restart and are removed from ISR. Producer sends a
> message m to A, and receives an acknowledgement. Disk failure happens in A
> before B and C replicate m. Message m is lost.
> In summary, any existing configuration cannot satisfy the requirements.
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