tinaselenge commented on code in PR #14382: URL: https://github.com/apache/kafka/pull/14382#discussion_r1325541025
########## docs/ops.html: ########## @@ -3859,6 +3859,98 @@ <h3>Finalizing the migration</h3> # Other configs ...</pre> + +<h3 class="anchor-heading"><a id="tiered_storage" class="anchor-link"></a><a href="#kraft">6.11 Tiered Storage</a></h3> + +<h4 class="anchor-heading"><a id="tiered_storage_overview" class="anchor-link"></a><a href="#tiered_storage_overview">Tiered Storage Overview</a></h4> + +<p>Kafka data is mostly consumed in a streaming fashion using tail reads. Tail reads leverage OS's page cache to serve the data instead of disk reads. + Older data is typically read from the disk for backfill or failure recovery purposes and is infrequent.</p> + +<p>In the tiered storage approach, Kafka cluster is configured with two tiers of storage - local and remote. + The local tier is the same as the current Kafka that uses the local disks on the Kafka brokers to store the log segments. + The new remote tier uses external storage systems, such as HDFS or S3, to store the completed log segments. + Please check <a href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-405%3A+Kafka+Tiered+Storage";>KIP-405</a> for more information. +</p> + +<p><b>Note: Tiered storage is considered as an early access feature, and is not recommended for use in production environments</b></p> + +<h4 class="anchor-heading"><a id="tiered_storage_config" class="anchor-link"></a><a href="#tiered_storage_config">Configuration</a></h4> + +<h5 class="anchor-heading"><a id="tiered_storage_config_broker" class="anchor-link"></a><a href="#tiered_storage_config_broker">Broker Configurations</a></h5> + +<p>By default, Kafka server will not enable tiered storage feature. <code>remote.log.storage.system.enable</code> + is the property to control whether to enable tiered storage functionality in a broker or not. Setting it to "true" to enable this feature. +</p> + +<p><code>RemoteStorageManager</code> is an interface to provide the lifecycle of remote log segments and indexes. Kafka server + doesn't provide out-of-the-box implementation of RemoteStorageManager. Configuring <code>remote.log.storage.manager.class.name</code> + and <code>remote.log.storage.manager.class.path</code> to specify the implementation of RemoteStorageManager. +</p> + +<p><code>RemoteLogMetadataManager</code> is an interface to provide the lifecycle of metadata about remote log segments with strongly consistent semantics. + By default, Kafka provides an implementation with storage as an internal topic. This implementation can be changed by configuring + <code>remote.log.metadata.manager.class.name</code> and <code>remote.log.metadata.manager.class.path</code>. + When adopting the default kafka internal topic based implementation, <code>remote.log.metadata.manager.listener.name</code> + is a mandatory property to specify which listener the clients created by the default RemoteLogMetadataManager implementation. +</p> + + +<h5 class="anchor-heading"><a id="tiered_storage_config_topic" class="anchor-link"></a><a href="#tiered_storage_config_topic">Topic Configurations</a></h5> + +<p>After correctly configuring broker side configurations for tiered storage feature, there are still configurations in topic level needed to be set. + <code>remote.storage.enable</code> is the switch to determine if this topic want to use tiered storage or not. By default it is set as false. + After enabling <code>remote.storage.enable</code> property, the next thing to consider is the log retention. + When tiered storage is enabled in the topic, there will be 2 additional log retention configuration to set: + +<ul> + <li><code>local.retention.ms</code></li> + <li><code>retention.ms</code></li> + <li><code>local.retention.bytes</code></li> + <li><code>retention.bytes</code></li> +</ul> + + The configuration prefixed with <code>local</code> are to specify the time/size the "local" log file can accept before moving to remote storage, and then get deleted. + If unset, The value in <code>retention.ms</code> and <code>retention.bytes</code> will be used. +</p> + +<h4 class="anchor-heading"><a id="tiered_storage_config_ex" class="anchor-link"></a><a href="#tiered_storage_config_ex">Configurations Example</a></h4> + +<p>Here is a sample configuration to enable tiered storage feature in broker side: +<pre> +# Sample Zookeeper/Kraft broker server.properties listening on PLAINTEXT://:9092 +remote.log.storage.system.enable=true +# Please provide the implementation for remoteStorageManager. This is the mandatory configuration for tiered storage. +# remote.log.storage.manager.class.name=org.apache.kafka.server.log.remote.storage.NoOpRemoteStorageManager +# Using the "PLAINTEXT" listener for the clients in RemoteLogMetadataManager to talk to the brokers. +remote.log.metadata.manager.listener.name=PLAINTEXT +</pre> +</p> + +<p>After broker is started, creating a topic with tiered storage enabled, and a small log time retention value to try this feature: +<pre>bin/kafka-topics.sh --create --topic tieredTopic --bootstrap-server localhost:9092 --config remote.storage.enable=true --config local.retention.ms=1000 +</pre> +</p> + +<p>Then, after the active segment is rolled, the old segment should be moved to the remote storage and get deleted. +</p> + +<h4 class="anchor-heading"><a id="tiered_storage_limitation" class="anchor-link"></a><a href="#tiered_storage_limitation">Limitations</a></h4> + +<p>While the early access release of Tiered Storage offers the opportunity to try out this new feature, it is important to be aware of the following limitations: +<ul> + <li>No support for clusters with multiple log directories (i.e. JBOD feature)</li> + <li>No support for compacted topics</li> + <li>Cannot disable tiered storage at the topic level</li> Review Comment: Does this mean, once enabled for a topic, you cannot disable it? -- This is an automated message from the Apache Git Service. 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