[KAFKA-1631] ReplicationFactor and under-replicated partitions incorrect during reassignment

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.8.1.1
• Labels: newbie
• Assignee: Ewen Cheslack-Postava
• Reporter: Ryan Berdeen
• Created: 11/Sep/14 21:36
• Updated: 05/Apr/15 02:58

Description

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:

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
...

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.