[jira] [Commented] (KAFKA-1631) ReplicationFactor and under-replicated partitions incorrect during reassignment

["Neha Narkhede (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-1631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14131051#comment-14131051 ] 

Neha Narkhede commented on KAFKA-1631:
--------------------------------------

Thanks for reporting the issue, [~rberdeen]. Since partition reassignment involves changing the replicas of a partition, it is tricky to report the under replicated status correctly at all times. However, one possible improvement is to change the topics tool to not report partitions being reassigned, as under replicated. It is a minor change, feel free to give it a stab.

> ReplicationFactor and under-replicated partitions incorrect during reassignment
> -------------------------------------------------------------------------------
>
>                 Key: KAFKA-1631
>                 URL: https://issues.apache.org/jira/browse/KAFKA-1631
>             Project: Kafka
>          Issue Type: Bug
>    Affects Versions: 0.8.1.1
>            Reporter: Ryan Berdeen
>              Labels: newbie
>
> We have a topic with a replication factor of 3. We monitor UnderReplicatedPartitions as recommended by the documentation.
> During a partition reassignment, partitions being reassigned are reported as under-replicated. Running a describe shows:
> {code}
> Topic:activity-wal-1    PartitionCount:15       ReplicationFactor:5     Configs:
>         Topic: activity-wal-1   Partition: 0    Leader: 14      Replicas: 14,13,12,11,15        Isr: 14,12,11,13
>         Topic: activity-wal-1   Partition: 1    Leader: 14      Replicas: 15,14,11      Isr: 14,11
>         Topic: activity-wal-1   Partition: 2    Leader: 11      Replicas: 11,15,12      Isr: 12,11,15
> ...
> {code}
> It looks like the displayed replication factor, 5, is simply the number of replicas listed for the first partition, which includes both brokers in the current list and those onto which the partition is being reassigned. Partition 0 is also included in the list when using the `--under-replicated-partitions` option, even though it is replicated to more partitions than the true replication factor.
> During a reassignment, the under-replicated partitions metric is not usable, meaning that actual under-replicated partitions can go unnoticed.



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