[jira] [Created] (KAFKA-15414) remote logs get deleted after partition reassignment

["Luke Chen (Jira)" <ji...@apache.org>]

Luke Chen created KAFKA-15414:
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             Summary: remote logs get deleted after partition reassignment
                 Key: KAFKA-15414
                 URL: https://issues.apache.org/jira/browse/KAFKA-15414
             Project: Kafka
          Issue Type: Bug
            Reporter: Luke Chen
         Attachments: image-2023-08-29-11-12-58-875.png

it seems I'm reaching that codepath when running reassignments on my cluster and segment are deleted from remote store despite a huge retention (topic created a few hours ago with 1000h retention).
It seems to happen consistently on some partitions when reassigning but not all partitions.

My test:

I have a test topic with 30 partition configured with 1000h global retention and 2 minutes local retention
I have a load tester producing to all partitions evenly
I have consumer load tester consuming that topic
I regularly reset offsets to earliest on my consumer to test backfilling from tiered storage.

My consumer was catching up consuming the backlog and I wanted to upscale my cluster to speed up recovery: I upscaled my cluster from 3 to 12 brokers and reassigned my test topic to all available brokers to have an even leader/follower count per broker.

When I triggered the reassignment, the consumer lag dropped on some of my topic partitions:
!image-2023-08-29-11-12-58-875.png|width=800,height=79! Screenshot 2023-08-28 at 20 57 09

Later I tried to reassign back my topic to 3 brokers and the issue happened again.

Both times in my logs, I've seen a bunch of logs like:

[RemoteLogManager=10005 partition=uR3O_hk3QRqsn4mPXGFoOw:loadtest11-17] Deleted remote log segment RemoteLogSegmentId

{topicIdPartition=uR3O_hk3QRqsn4mPXGFoOw:loadtest11-17, id=Mk0chBQrTyKETTawIulQog}

due to leader epoch cache truncation. Current earliest epoch: EpochEntry(epoch=14, startOffset=46776780), segmentEndOffset: 46437796 and segmentEpochs: [10]

Looking at my s3 bucket. The segments prior to my reassignment have been indeed deleted.



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