A colleague says "Kafka has diskless topics now, so we can drop the broker disks." How do you respond?

Diskless topics are KIP-1150, whose status is Accepted. Acceptance covers only the need for the feature: the KIP requires no code changes and adds no public interfaces, and the implementation sits in follow-up KIPs (KIP-1163 Diskless Core and KIP-1164 Diskless Coordinator). None of the 4.1.0, 4.2.0 or 4.3.0 release announcements mention it, so Apache Kafka does not ship it. What exists today is tiered storage, production-ready since 3.9, which moves old segments to remote storage but still keeps recent data on local disks with ISR replication. Some vendors sell their own storage designs, which is a different product, so ask which implementation is meant and measure any cost claims against your own workload.

Expected key concepts: KIP-1150, diskless, tiered storage, remote storage, ISR, accepted, follow-up KIPs, vendor, 3.9, local disk