cmccabe commented on code in PR #14160:
URL: https://github.com/apache/kafka/pull/14160#discussion_r1406786425
##########
docs/ops.html:
##########
@@ -3603,39 +3603,45 @@ <h4 class="anchor-heading"><a id="kraft_missing"
class="anchor-link"></a><a href
<ul>
<li>Supporting JBOD configurations with multiple storage directories</li>
<li>Modifying certain dynamic configurations on the standalone KRaft
controller</li>
- <li>Delegation tokens</li>
</ul>
<h4 class="anchor-heading"><a id="kraft_zk_migration"
class="anchor-link"></a><a href="#kraft_zk_migration">ZooKeeper to KRaft
Migration</a></h4>
<p>
<b>ZooKeeper to KRaft migration is considered an Early Access feature and
is not recommended for production clusters.</b>
+ Please report issues with ZooKeeper to KRaft migration using the
+ <a href="https://issues.apache.org/jira/projects/KAFKA";
target="_blank">project JIRA</a> and the "kraft" component.
</p>
- <p>The following features are not yet supported for ZK to KRaft
migrations:</p>
-
+ <h3>Terminology</h3>
<ul>
- <li>Downgrading to ZooKeeper mode during or after the migration</li>
- <li>Other features <a href="#kraft_missing">not yet supported in
KRaft</a></li>
+ <li>Brokers that are in <b>ZK mode</b> store their metadata in Apache
ZooKepeer. This is the old mode of handling metadata.</li>
+ <li>Brokers that are in <b>KRaft mode</b> store their metadata in a KRaft
quorum. This is the new and improve mode of handling metadata.</li>
+ <li><b>Migration</b> is the process of moving cluster metadata from
ZooKeeper into a KRaft quorum.</li>
</ul>
- <p>
- Please report issues with ZooKeeper to KRaft migration using the
- <a href="https://issues.apache.org/jira/projects/KAFKA";
target="_blank">project JIRA</a> and the "kraft" component.
- </p>
+ <h3>Migration Phases</h3>
+ In general, the migration process passes through several phases.
- <h3>Terminology</h3>
- <p>
- We use the term "migration" here to refer to the process of changing a
Kafka cluster's metadata
- system from ZooKeeper to KRaft and migrating existing metadata. An
"upgrade" refers to installing a newer version of Kafka. It is not recommended
to
- upgrade the software at the same time as performing a metadata migration.
- </p>
+ <ul>
+ <li>In the <b>initial phase</b>, all the brokers are in ZK mode, and there
is a ZK-based controller.</li>
+ <li>During the <b>initial metadata load</b>, a KRaft quorum loads the
metadata from ZooKeeper,</li>
+ <li>In <b>hybrid phase</b>, some brokers are in ZK mode, but there is a
KRaft controller.</li>
+ <li>In <b>dual-write phase</b>, all brokers are KRaft, but the KRaft
controller is continuing to write to ZK.</li>
+ <li>When the migration has been <b>finalized</b>, we no longer write
metadata to ZooKeeper.</li>
+ </ul>
- <p>
- We also use the term "ZK mode" to refer to Kafka brokers which are using
ZooKeeper as their metadata
- system. "KRaft mode" refers Kafka brokers which are using a KRaft
controller quorum as their metadata system.
- </p>
+ <h3>Limitations</h3>
+ <ul>
+ <li>While a cluster is being migrated from ZK mode to KRaft mode, we do
not support changing the <i>metadata
+ version</i> (also known as the <i>inter.broker.protocol</i> version.)
Please do not attempt to do this during
+ a migration, or you may break the cluster.</li>
+ <li>After the migration has been finalized, it is not possible to revert
back to ZooKeeper mode.</li>
+ <li><a href="#kraft_missing">As noted above</a>, some features are not
fully implemented in KRaft mode. If you are
+ using one of those features, you will not be able to migrate to KRaft
yet.</li>
+ </ul>
+ </ul>
Review Comment:
removed
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
