Hi Anton, Thanks for the KIP, in my opinion it is really important to cover edge cases like this as the migration can be already tricky enough.
HG1: Using the `--zk-rollback-compatible` flag eliminates the compatibility issue but the operator is still at the mercy of knowing about the flag before executing the formatting command. Chances are that the very same issue will come up even with a kafka-storage tool updated with your fix as the flag will be omitted for various reasons. Would it make sense to add a reformatting ability to the kafka-storage tool to recover the rollback scenario? Also we could include a more detailed error message when the broker crashes in ZK mode about the reformatting possibility. My second question is actually aimed at the project maintainers, I hope it is not too off-topic here. I have recently discovered that Kafka 3.9.2 was moved to archived releases. What does this mean exactly for contributions/KIPs like this targeting the 3.9 branch? Given enough interest is it still possible to have a 3.9.3 release? Thanks, Gergely On Thu, 9 Jul 2026 at 12:18, Anton Agestam via dev <[email protected]> wrote: > Hi everyone, > > I would like to start the discussion for KIP-1362: Add a > rollback-compatible storage format option for KRaft migration. > > KIP: > > https://cwiki.apache.org/confluence/spaces/KAFKA/pages/440303727/KIP-1362+Add+a+rollback-compatible+storage+format+option+for+KRaft+migration > Jira: https://issues.apache.org/jira/browse/KAFKA-20762 > PR/reference implementation: https://github.com/apache/kafka/pull/22751 > > In summary: this KIP proposes closing a current gap, where the ability to > do rollback of an ongoing KRaft migration breaks when cluster member nodes > are replaced. The proposed solution is to add a CLI flag to the storage > formatting tool that causes the resulting storage to not break when rolled > back. > > I'm looking forward to feedback on this proposal. > > Thanks, > Anton > > -- > [image: Aiven] <https://www.aiven.io/> > *Anton Agestam* (he/him or they/them) > Software Engineer, *Aiven* > [email protected] | +46 704 486 289 > aiven.io <https://www.aiven.io/> | > <https://www.facebook.com/aivencloud> > <https://www.linkedin.com/company/aiven/> <https://twitter.com/aiven_io > > >
