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Authors: Mehari Beyene, Divij Vaidya

Collaborators: Karthik Rajagopalan, Nagarjuna Koduru

Status

Current state:"Draft"

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1. System-Wide Disablement: The tiered storage disablement feature does not aim to support the system-wide disablement of tiered storage on a cluster level, as this is controlled by the cluster-level configuration remote.log.storage.system.enable.
2. Support for Compacted Topics: Tiered Storage is not supported for compacted topics, and this behavior will remain unchanged. During re-enablement, the feature will not support tiered storage for compacted topics. When initially enabling tiered storage for a topic, we check that the topic does not have compaction enabled, however, if the topic has historically used a compaction policy, we do not perform deep check to restrict tiered storage enablement. This behavior will remain consistent during re-enablement as well.

Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

A public interface is any change to the following:

• Binary log format

• The network protocol and api behavior

• Any class in the public packages under clientsConfiguration, especially client configuration

  • org/apache/kafka/common/serialization

  • org/apache/kafka/common

  • org/apache/kafka/common/errors

  • org/apache/kafka/clients/producer

  • org/apache/kafka/clients/consumer (eventually, once stable)

• Monitoring

• Command line tools and arguments

• Anything else that will likely break existing users in some way when they upgrade

Proposed Changes

Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

Compatibility, Deprecation, and Migration Plan

• What impact (if any) will there be on existing users?
• If we are changing behavior how will we phase out the older behavior?
• If we need special migration tools, describe them here.
• When will we remove the existing behavior?

Test Plan

Describe in few sentences how the KIP will be tested. We are mostly interested in system tests (since unit-tests are specific to implementation details). How will we know that the implementation works as expected? How will we know nothing broke?

Rejected Alternatives

Proposed Changes

Concepts

Remote Log Disablement Policy

When disabling tiered storage on a topic, users will have the option of retaining or deleting the remote log at the time of disablement. This is represented by a remote log disablement policy. It will be an optional policy that users can specify. By default, we will retain the remote log.

• remote.log.disable.policy=retain: Logs that are archived in the remote storage will be part of the contiguous "active" log. Clients can fetch the archived log, but no new data will be archived to the remote storage.
• remote.log.disable.policy=delete: Logs that are archived in the remote storage will not be part of the contiguous "active" log and will be deleted asynchronously as part of the disablement process.

Tiered Epoch

The tiered epoch signifies the version of a tiered storage topic. This epoch establishes a boundary for the transition from the enabling to disabling state, preventing concurrent and out-of-order modifications. Its aim is to guarantee that all activities within the disablement process are fully completed before permitting the re-enablement of tiering.

State Transitions

When users disable tiered storage on a topic, the tiered storage state on a topic transitions through the following stages: ENABLED → DISABLING → DISABLEDIf there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.