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https://issues.apache.org/jira/browse/KAFKA-1050?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13761530#comment-13761530
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Jay Kreps commented on KAFKA-1050:
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Or actually, perhaps I am confused. The data loss case is (2) and it would
definitely be good to implement a case where we wait on an in-sync replica
rather than allowing an unsafe election. I don't think (1) actually helps
though. Basically in a majority vote scenario (which I think you are calling
quorum, though I think both approaches are quorums) this is the equivalent to
throwing an exception if you can only get 3/5 to commit. In a sense this does
increase the chance of durability since more servers wrote it, but it is also a
bit odd to intentionally fail your own successful writes.
> Support for "no data loss" mode
> -------------------------------
>
> Key: KAFKA-1050
> URL: https://issues.apache.org/jira/browse/KAFKA-1050
> Project: Kafka
> Issue Type: Task
> Reporter: Justin SB
>
> I'd love to use Apache Kafka, but for my application data loss is not
> acceptable. Even at the expense of availability (i.e. I need C not A in CAP).
> I think there are two things that I need to change to get a quorum model:
> 1) Make sure I set request.required.acks to 2 (for a 3 node cluster) or 3
> (for a 5 node cluster) on every request, so that I can only write if a quorum
> is active.
> 2) Prevent the behaviour where a non-ISR can become the leader if all ISRs
> die. I think this is as easy as tweaking
> core/src/main/scala/kafka/controller/PartitionLeaderSelector.scala,
> essentially to throw an exception around line 64 in the "data loss" case.
> I haven't yet implemented / tested this. I'd love to get some input from the
> Kafka-experts on whether my plan is:
> (a) correct - will this work?
> (b) complete - have I missed any cases?
> (c) recommended - is this a terrible idea :-)
> Thanks for any pointers!
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