Kafka Cluster Types in Confluent Cloud¶
Confluent offers different types of Kafka clusters in Confluent Cloud. The cluster type you choose determines the features, capabilities, and price of the cluster. Use the information in this topic to find the cluster with the features and capabilities that best meets your needs. Use Basic clusters for experimentation and early development. For a production cluster, choose from Standard, Enterprise, or Dedicated.
The table below offers a high-level comparison of features across Kafka cluster types.
* RBAC roles for resources within the Kafka cluster (DeveloperRead, DeveloperWrite, DeveloperManage, and ResourceOwner) are not available on Basic clusters.
† Stream Sharing does not support every private networking option.
** Source only
†† Source only depending on network type
Important
The capabilities provided in this topic are for planning purposes, and are not a guarantee of performance, which varies depending on each unique configuration.
Cluster limit comparison¶
Use the table below to compare cluster limits across cluster types.
Dimension | Basic | Standard | Enterprise | Dedicated |
---|---|---|---|---|
Ingress (MBps) * † | 250 | 250 | 600 | 9,120 |
Egress (MBps) * † | 750 | 750 | 1800 | 27,360 |
Partitions (pre-replication - for non-compacted topics) * † | 4096 | 4096 | 30,000 | 100,000 |
Total client connections * † | 1000 | 1000 | 45,000 | 2,736,000 |
Connection attempts (per second) * † | 80 | 80 | 2500 | 76,000 |
Requests (per second) * † | 15,000 | 15,000 | 75,000 | 2,280,000 |
Message size (MB) | 8 | 8 | 20 | 20 |
Client version (minimum) | 0.11.0 | 0.11.0 | 0.11.0 | 0.11.0 |
Request size (MB) | 100 | 100 | 100 | 100 |
Fetch bytes (MB) | 55 | 55 | 55 | 55 |
API keys | 50 | 100 | 500 | 2,000 |
Partition creation and deletion (per five minute period) | 250 | 500 | 500 | 5,000 |
Connector tasks per Kafka cluster | 250 | 250 | 250 | 250 |
ACLs | 1,000 | 1,000 | 4,000 | 10,000 |
Kafka REST Produce v3 - Max throughput (MBps): | 10 | 10 | 10 | 7,600 † |
Kafka REST Produce v3 - Max connection requests (per second): | 25 | 25 | 25 | 45,600 † |
Kafka REST Produce v3 - Max streamed requests (per second): | 1000 | 1000 | 1000 | 456,000 † |
Kafka REST Produce v3 - Max message size for Kafka REST Produce API (MB): | 8 | 8 | 8 | 20 |
Kafka REST Admin v3 - Max connection requests (per second): | 25 | 25 | 25 | 45,600 † |
* Limit based on Elastic Confluent Unit for Kafka (eCKU). You only pay for the capacity you use up to the limit. For more information, see Elastic Confluent Unit for Kafka.
† Limit based on a Dedicated Kafka cluster with 152 CKU. For more information, see CKU limits per cluster and Confluent Unit for Kafka.
eCKU/CKU comparison¶
The table below compares limits for a single billing unit for each cluster type.
Basic, Standard, and Enterprise clusters are elastic, shrinking and expanding automatically based on load. You don’t resize these clusters (unlike Dedicated clusters). When you need more capacity, your cluster expands up to the fixed ceiling. If you’re not using capacity above the minimum, you’re not paying for it. If you’re at zero capacity, you don’t pay for anything.
Dimension | Basic eCKU | Standard eCKU | Enterprise eCKU | Dedicated CKU |
---|---|---|---|---|
Ingress (MBps) | 5 | 25 | 60 | 60 |
Egress (MBps) | 15 | 75 | 180 | 180 |
Partitions (pre-replication - for non-compacted topics) | 30 | 250 | 3,000 (360 compacted) | 4,500 |
Total client connections | 20 | 1000 | 4,500 | 18,000 |
Connection attempts (per second) | 5 | 50 | 250 | 500 |
Requests (per second) | 100 | 1,500 | 7,500 | 15,000 |
Kafka REST Produce v3 - Max throughput (MBps): | N/a | N/a | N/a | 50 |
Kafka REST Produce v3 - Max connection requests (per second): | N/a | N/a | N/a | 300 |
Kafka REST Produce v3 - Max streamed requests (per second): | N/a | N/a | N/a | 3000 |
Kafka REST Admin v3 - Max connection requests (per second): | N/a | N/a | N/a | 300 |
Pricing changes for Basic/Standard clusters
Beginning 4/16/2024, the pricing model for Basic & Standard clusters will utilize Elastic CKUs (eCKU) instead of Base & Partitions. These changes are only applicable to Confluent Cloud organizations created on or after 4/16/2024. All organizations created before this date are not impacted and will continue to utilize their existing cluster pricing model and limits.
If you have any questions, please contact us by creating a Support request via the Confluent Cloud Support Portal or by reaching out to your account team.
Basic clusters¶
Basic Kafka clusters are designed for experimentation, early development, and basic use cases. Basic clusters support the following:
- 99.5% uptime SLA
- Up to 1 GB/s of throughput and 5 TB of storage.
- Can be upgraded to a higher uptime SLA Standard cluster at any time using the Confluent Cloud Console.
- Automatic scaling based on load
You can view connector events in Confluent Cloud Console with a Basic cluster, but you can’t consume events from a topic using Confluent CLI, Java, or C/C++. For more information, see View Connector Events.
Confluent uses Elastic Confluent Unit for Kafka (eCKU) to provision and bill for Basic Kafka clusters.
Pricing changes for Basic/Standard clusters
Beginning 4/16/2024, the pricing model for Basic & Standard clusters will utilize Elastic CKUs (eCKU) instead of Base & Partitions. These changes are only applicable to Confluent Cloud organizations created on or after 4/16/2024. All organizations created before this date are not impacted and will continue to utilize their existing cluster pricing model and limits.
If you have any questions, please contact us by creating a Support request via the Confluent Cloud Support Portal or by reaching out to your account team.
eCKU limits per Basic cluster¶
Basic clusters are elastic, shrinking and expanding automatically based on load. You don’t resize your cluster. When you need more capacity, your Basic cluster expands up to the fixed ceiling. If you’re not using capacity above the minimum, you’re not paying for it.
Basic cluster capacity:
- Minimum: 1 eCKU *
- Fixed ceiling: 50 eCKU
* If consumption in a given hour is zero across all billable dimensions, you pay nothing. For more information, see Elastic Confluent Unit for Kafka.
eCKU capacity guidance¶
The dimensions in the following table describe the capacity of a single eCKU. For more information about eCKU, see Elastic Confluent Unit for Kafka and Compare Billing Units for Kafka clusters.
Dimension | eCKU capacity |
---|---|
Ingress | 5 megabytes per second (MBps) |
Egress | 15 megabytes per second (MBps) |
Partitions (pre-replication) | 30 partitions for non-compacted topics |
Total client connections | 20 connections |
Connection attempts | 5 connection attempts per second |
Requests | 100 requests per second |
Basic limits per cluster¶
Dimension | Capability | Additional details |
---|---|---|
Ingress | Max 250 MBps | Number of bytes that can be produced to the cluster in one second. Available in the Metrics API as If you are self-managing Kafka, you can look at the producer outgoing-byte-rate metrics and broker kafka.server:type=BrokerTopicMetrics,name=BytesInPerSec metrics to understand your throughput. To reduce usage on this dimension, you can compress your messages.
|
Egress | Max 750 MBps | Number of bytes that can be consumed from the cluster in one second. Available in the the Metrics API as If you are self-managing Kafka, you can look at the consumer incoming-byte-rate metrics and broker kafka.server:type=BrokerTopicMetrics,name=BytesOutPerSec to understand your throughput. To reduce usage on this dimension, you can compress your messages
and ensure each consumer is only consuming from the topics it requires. |
Storage (pre-replication) | Max 5 TB | Number of bytes retained on the cluster, pre-replication. Available in the Metrics API as You can configure policy settings If you are self-managing Kafka, you can look at how much disk space your cluster is using to understand your storage needs. To reduce usage on this dimension, you can
compress your messages
and reduce your retention settings.
|
Partitions (pre-replication) | Max 4096 | Maximum number of partitions that can exist on the cluster at one time, before replication.
All topics that the customer creates as well as internal topics that are automatically created
by Confluent Platform components–such as ksqlDB, Kafka Streams, Connect, and Control Center–count towards the cluster
partition limit. The automatically created topics are prefixed with an underscore ( Available in the Metrics API as Attempts to create additional partitions beyond this limit will fail with an error message. If you are self-managing Kafka, you can look at the To reduce usage on this dimension, you can delete unused topics and create new topics with fewer partitions. You can use the Kafka Admin interface to increase the partition count of an existing topic if the initial partition count is too low. |
Total client connections | Max 1000 | Number of TCP connections to the cluster that can be open at one time. Available
in the Metrics API as If you are self-managing Kafka, you can look at the broker kafka.server:type=socket-server-metrics,listener={listener_name},networkProcessor={#},name=connection-count metrics to understand how many connections you are using. This value may not have a 1:1 ratio to connections in Confluent Cloud, depending on the number of brokers, partitions, and applications in your self-managed cluster. How many connections a cluster supports can vary widely based on several factors, including number of producer clients, number of consumer clients, partition keying strategy, produce patterns per client, and consume patterns per client. |
Connection attempts | Max 80 per second | Maximum number of new TCP connections to the cluster that can be created in one second. This means successful authentications plus unsuccessful authentication attempts. Available in the Metrics API as If you are self-managing Kafka, you can look at the rate of change for the
kafka.server:type=socket-server-metrics,listener={listener_name},networkProcessor={#},name=connection-count metric and
the Consumer To reduce usage on this dimension, you can use longer-lived connections to the cluster. |
Requests | Max ~ 15,000 per second | Number of client requests to the cluster in one second. Available in the the Metrics API as If you are self-managing Kafka, you can look at the broker kafka.network:type=RequestMetrics,name=RequestsPerSec,request={Produce FetchConsumer FetchFollower} metrics and client request-rate metrics to understand your request volume. To reduce usage on this dimension, you can adjust producer batching configurations, consumer client batching configurations, and shut down otherwise inactive clients. |
Message size | Max 8 MB | For message size defaults at the topic level see Kafka topic configurations for all Confluent Cloud cluster types. |
Client version | Minimum 0.11.0 | None |
Request size | Max 100 MB | None |
Fetch bytes | Max 55 MB | None |
API keys | Default limit 50 | You can request an increase. For more information, see Service Quotas for Confluent Cloud. |
Partition creation and deletion | Max 250 per 5 minute period | The following occurs when partition creation and deletion rate limit is reached:
|
Connector tasks per Kafka cluster | Max 250 | 1 task per connector |
ACLs | Default limit 1,000 | None |
Kafka REST Produce v3 | Max throughput: 10 MBps Max connection requests: 25 connection requests per second Max streamed requests: 1000 requests per second Max message size for Kafka REST Produce API: 8 MB |
Client applications can connect over the REST API to Produce records directly to the Confluent Cloud cluster. To learn more, see the Kafka REST concepts overview. The max connection requests limit is shared between Produce and Admin v3. For example, if Produce is running at 20 connection requests per second, Admin can run at five connection requests per second maximum. To learn more about the Kafka REST Produce API streaming mode, see the examples and explanation of streaming mode in the concept docs, and the Produce example in the quick start. A streamed request is a single record to be produced to Kafka. Concatenate the records to produce multiple records in the same request. Delivery reports are concatenated in the same order as the records are sent. For more information, see Produce Records. |
Kafka REST Admin v3 | Max connection requests: up to 25 connection requests per second | This limit is shared between Produce and Admin v3. For example, if Produce is running at 20 connection requests per second, Admin can run at approximately five connection requests per second maximum. |
Basic limits per partition¶
The partition capabilities that follow are based on benchmarking and intended as practical guidelines for planning purposes. Performance per partition will vary depending on your individual configuration, and these benchmarks do not guarantee performance.
Dimension | Capability |
---|---|
Ingress per Partition | ~5 MBps |
Egress per Partition | ~15 MBps |
Storage per Partition | Unlimited |
Storage per Partition for Compacted Topics | Unlimited |
Cluster Linking capabilities¶
- A Basic cluster can be a source cluster of a cluster link (can send data).
- A Basic cluster cannot be a destination cluster (cannot receive data).
To learn more, see Supported cluster types in the Cluster Linking documentation.
Standard clusters¶
Standard clusters are designed for production-ready features and functionality. Standard clusters support the following:
- Uptime SLA: 99.9% for 1 eCKU cluster minimum, 99.99% for 2 eCKU cluster minimum
- Up to 1 GB/s of throughput and unlimited storage.
- Multi-zone high availability cluster is spread across three availability zones for better resiliency.
- Automatic scaling based on load
Confluent uses Elastic Confluent Unit for Kafka (eCKU) to provision and bill for Standard Kafka clusters.
Pricing changes for Basic/Standard clusters
Beginning 4/16/2024, the pricing model for Basic & Standard clusters will utilize Elastic CKUs (eCKU) instead of Base & Partitions. These changes are only applicable to Confluent Cloud organizations created on or after 4/16/2024. All organizations created before this date are not impacted and will continue to utilize their existing cluster pricing model and limits.
If you have any questions, please contact us by creating a Support request via the Confluent Cloud Support Portal or by reaching out to your account team.
eCKU limits per Standard cluster¶
Standard clusters are elastic, shrinking and expanding automatically based on load. You don’t resize your cluster. When you need more capacity, your Standard cluster expands up to the fixed ceiling. If you’re not using capacity above the minimum, you’re not paying for it.
Standard cluster capacity:
- Minimum: Depends on SLA requirements *
- 99.9% uptime SLA: 1 eCKU minimum
- 99.99% uptime SLA: 2 eCKU minimum
- Fixed ceiling: 10 eCKU
Your cluster scales to meet demand or save costs but your SLA does not change. You can upgrade a Standard cluster from 99.9% uptime to 99.99% uptime SLA. Standard SLA upgrades changes the minimum cluster capacity from 1 to 2 eCKU.
* If consumption in a given hour is zero across all billable dimensions, you pay nothing. For more information, see Elastic Confluent Unit for Kafka.
eCKU capacity guidance¶
The dimensions in the following table describe the capacity of a single eCKU. For more information about eCKU, see Elastic Confluent Unit for Kafka and Compare Billing Units for Kafka clusters.
Dimension | eCKU capacity |
---|---|
Ingress | 25 megabytes per second (MBps) |
Egress | 75 megabytes per second (MBps) |
Partitions (pre-replication) | 250 partitions for non-compacted topics |
Total client connections | 1000 connections |
Connection attempts | 50 connection attempts per second |
Requests | 1,500 requests per second |
Standard limits per cluster¶
Dimension | Capability | Additional details |
---|---|---|
Ingress | Max 250 MBps | Number of bytes that can be produced to the cluster in one second. Available in the Metrics API as If you are self-managing Kafka, you can look at the producer outgoing-byte-rate metrics and broker kafka.server:type=BrokerTopicMetrics,name=BytesInPerSec metrics to understand your throughput. To reduce usage on this dimension, you can compress your messages.
|
Egress | Max 750 MBps | Number of bytes that can be consumed from the cluster in one second. Available in the the Metrics API as If you are self-managing Kafka, you can look at the consumer incoming-byte-rate metrics and broker kafka.server:type=BrokerTopicMetrics,name=BytesOutPerSec to understand your throughput. To reduce usage on this dimension, you can compress your messages
and ensure each consumer is only consuming from the topics it requires. |
Storage (pre-replication) | Infinite | Number of bytes retained on the cluster, pre-replication. Standard Confluent Cloud clusters support Infinite Storage. This means there is no maximum size limit for the amount of data that can be stored on the cluster. Available in the Metrics API as You can configure policy settings If you are self-managing Kafka, you can look at how much disk space your cluster is using to understand your storage needs. To reduce usage on this dimension, you can
compress your messages
and reduce your retention settings.
|
Partitions (pre-replication) | Max 4096 | Maximum number of partitions that can exist on the cluster at one time, before replication.
All topics that the customer creates as well as internal topics that are automatically created
by Confluent Platform components–such as ksqlDB, Kafka Streams, Connect, and Control Center–count towards the cluster
partition limit. The automatically created topics are prefixed with an underscore ( Available in the Metrics API as Attempts to create additional partitions beyond this limit will fail with an error message. If you are self-managing Kafka, you can look at the To reduce usage on this dimension, you can delete unused topics and create new topics with fewer partitions. You can use the Kafka Admin interface to increase the partition count of an existing topic if the initial partition count is too low. |
Total client connections | Max 1000 | Number of TCP connections to the cluster that can be open at one time. Available
in the Metrics API as If you are self-managing Kafka, you can look at the broker kafka.server:type=socket-server-metrics,listener={listener_name},networkProcessor={#},name=connection-count metrics to understand how many connections you are using. This value may not have a 1:1 ratio to connections in Confluent Cloud, depending on the number of brokers, partitions, and applications in your self-managed cluster. How many connections a cluster supports can vary widely based on several factors, including number of producer clients, number of consumer clients, partition keying strategy, produce patterns per client, and consume patterns per client. |
Connection attempts | Max 80 per second | Maximum number of new TCP connections to the cluster that can be created in one second. This means successful authentications plus unsuccessful authentication attempts. Available in the Metrics API as If you are self-managing Kafka, you can look at the rate of change for the
kafka.server:type=socket-server-metrics,listener={listener_name},networkProcessor={#},name=connection-count metric and
the Consumer To reduce usage on this dimension, you can use longer-lived connections to the cluster. |
Requests | Max ~ 15,000 per second | Number of client requests to the cluster in one second. Available in the the Metrics API as If you are self-managing Kafka, you can look at the broker kafka.network:type=RequestMetrics,name=RequestsPerSec,request={Produce FetchConsumer FetchFollower} metrics and client request-rate metrics to understand your request volume. To reduce usage on this dimension, you can adjust producer batching configurations, consumer client batching configurations, and shut down otherwise inactive clients. |
Message size | Max 8 MB | For message size defaults at the topic level, see Kafka topic configurations for all Confluent Cloud cluster types. |
Client version | Minimum 0.11.0 | None |
Request size | Max 100 MB | None |
Fetch bytes | Max 55 MB | None |
API keys | Default limit 100 | You can request an increase. For more information, see Service Quotas for Confluent Cloud. |
Partition creation and deletion | Max 500 per 5 minute period | The following occurs when partition creation and deletion rate limit is reached:
|
Connector tasks per Kafka cluster | Max 250 | None |
ACLs | Default limit 1,000 | None |
Kafka REST Produce v3 | Max throughput: 10 MBps Max connection requests: 25 connection requests per second Max streamed requests: 1000 requests per second Max message size for Kafka REST Produce API: 8 MB |
Client applications can connect over the REST API to Produce records directly to the Confluent Cloud cluster. To learn more, see the Kafka REST concepts overview. The max connection requests limit is shared between Produce and Admin v3. For example, if Produce is running at 20 connection requests per second, Admin can run at five connection requests per second maximum. To learn more about the Kafka REST Produce API streaming mode, see the examples and explanation of streaming mode in the concept docs, and the Produce example in the quick start. A streamed request is a single record to be produced to Kafka. Concatenate the records to produce multiple records in the same request. Delivery reports are concatenated in the same order as the records are sent. For more information, see Produce Records. |
Kafka REST Admin v3 | Max connection requests: up to 25 connection requests per second | This limit is shared between Produce and Admin v3. For example, if Produce is running at 20 connection requests per second, Admin can run at approximately five connection requests per second maximum. |
Standard limits per partition¶
The partition capabilities that follow are based on benchmarking and intended as practical guidelines for planning purposes. Performance per partition will vary depending on your individual configuration, and these benchmarks do not guarantee performance.
Dimension | Capability |
---|---|
Ingress per Partition | ~5 MBps |
Egress per Partition | ~15 MBps |
Storage per Partition | Unlimited |
Storage per Partition for Compacted Topics | Unlimited |
Cluster Linking capabilities¶
- A Standard cluster can be a source cluster of a cluster link (can send data).
- A Standard cluster cannot be a destination cluster (cannot receive data).
To learn more, see Supported cluster types in the Cluster Linking documentation.
Enterprise clusters¶
Enterprise clusters are designed for production-ready functionality that requires private endpoint networking capabilities. Enterprise clusters support the following:
- Uptime SLA: 99.9% for 1 eCKU cluster minimum, 99.99% for 2 eCKU cluster minimum
- Up to 2.4 GB/s of throughput and unlimited storage
- Multi-zone high availability cluster spread across three availability zones for better resiliency
- Automatic scaling based on load
Confluent uses Elastic Confluent Unit for Kafka (eCKU) to provision and bill for Enterprise Kafka clusters.
eCKU limits per Enterprise cluster¶
Enterprise clusters are elastic, shrinking and expanding automatically based on load. You don’t resize your cluster. When you need more capacity, your Enterprise cluster expands up to the fixed ceiling. If you’re not using capacity above the minimum, you’re not paying for it.
Enterprise cluster capacity:
- Minimum: Depends on SLA requirements *
- 99.9% uptime SLA: 1 eCKU minimum
- 99.99% uptime SLA: 2 eCKUs minimum
- Fixed ceiling: 10 eCKU
Your cluster scales to meet demand or save costs but your SLA does not change. You can upgrade a Enterprise cluster from 99.9% uptime to 99.99% uptime SLA. Enterprise SLA upgrades changes the minimum cluster capacity from 1 to 2 eCKUs.
* If consumption in a given hour is zero across all billable dimensions, you pay nothing. For more information, see Elastic Confluent Unit for Kafka.
eCKU capacity guidance¶
The dimensions in the following table describe the capacity of a single eCKU. For more information about eCKU, see Elastic Confluent Unit for Kafka and Compare Billing Units for Kafka clusters.
Dimension | eCKU capacity |
---|---|
Ingress | 60 megabytes per second (MBps) |
Egress | 180 megabytes per second (MBps) |
Partitions (pre-replication) | 3,000 partitions for non-compacted topics, 360 for compacted topics |
Total client connections | 4,500 connections |
Connection attempts | 250 connection attempts per second |
Requests | 7,500 requests per second |
Enterprise limits per cluster¶
Enterprise clusters have a maximum capacity of 10 eCKU. For any Confluent Cloud cluster, the expected performance for any given workload is dependent on a variety of dimensions, such as message size and number of partitions.
Use the information in the following tables to determine if a given workload fits within the fixed ceiling, how to monitor dimensions, and suggestions to reduce your use of a particular dimension.
Dimension | Limits per cluster |
---|---|
Ingress * | 600 megabytes per second (MBps) |
Egress * | 1800 megabytes per second (MBps) |
Storage (pre-replication) * | Infinite |
Partitions (pre-replication) * | 30,000 partitions for non-compacted topics, 3600 for compacted topics |
Total client connections * | 45,000 connections |
Connection attempts * | 2500 connection attempts per second |
Requests * | 75,000 requests per second |
Message size | Max 20 MB |
Client version | Minimum 0.11.0 |
Request size | Max 100 MB |
Fetch bytes | Max 55 MB |
API keys | Default limit 500 (You can request an increase. For more information, see Service Quotas for Confluent Cloud.) |
Partition creation and deletion | Max 500 per 5 minute period |
Connector tasks per Kafka cluster | Max 250 |
ACLs | Default limit 4,000 |
Kafka REST Produce v3 | Max throughput: 10 MBps Max connection requests: 25 connection requests per second Max streamed requests: 1000 requests per second Max message size for Kafka REST Produce API: 8 MB |
* Dimension is per eCKU
. For more information, see eCKU limits per Enterprise cluster.
Enterprise limits per partition¶
The partition capabilities that follow are based on benchmarking and intended as practical guidelines for planning purposes. Performance per partition will vary depending on your individual configuration, and these benchmarks do not guarantee performance.
Dimension | Capability |
---|---|
Ingress per Partition | ~6 MBps |
Egress per Partition | ~18 MBps |
Storage per Partition | Unlimited |
Storage per Partition for Compacted Topics | Unlimited |
Cluster Linking capabilities¶
Enterprise clusters can be a source of a cluster link, dependent on the networking type and the other cluster involved. To learn more, see Supported cluster types in the Cluster Linking documentation.
Dedicated clusters¶
Dedicated clusters are designed for critical production workloads with high traffic or private networking requirements. Dedicated clusters support the following:
- Single-tenant deployments with a 99.95% uptime SLA for Single-Zone, and 99.99% for Multi-Zone
- Private networking options including VPC peering, AWS Transit Gateway, AWS PrivateLink, and Azure PrivateLink.
- Self-managed keys when AWS, Azure, or Google Cloud is the cloud service provider.
- Multi-zone high availability (optional). A multi-zone cluster is spread across three availability zones for better resiliency.
- Can be scaled to achieve gigabytes per second of ingress.
- Simple scaling in terms of CKUs.
- Cluster expansion, and Cluster shrinking.
- Cluster Linking for fully-managed replication (multiregion, multicloud, hybrid cloud, and inter-organization).
Dedicated clusters are provisioned and billed in terms of Confluent Unit for Kafka (CKU). CKUs are a unit of horizontal scalability in Confluent Cloud that provide a pre-allocated amount of resources. How much you can ingest and stream per CKU depends on a variety of factors including client application design and partitioning strategy. For more information, see Monitor Dedicated Clusters in Confluent Cloud and Dedicated Cluster Performance and Expansion in Confluent Cloud.
CKU limits per cluster¶
Dedicated clusters can be purchased in any whole number of CKUs up to a limit.
- For organizations with credit card billing, the upper limit is 4 CKUs per Dedicated cluster. Clusters up to 152 * CKUs are available by request.
- For organizations with integrated cloud provider billing or payment using an invoice, the upper limit is 24 CKUs per Dedicated cluster. Clusters up to 152 * CKUs are available by request.
For clusters that can scale to 152 * CKU, contact Confluent Support to discuss the onboarding process and product considerations.
Single-zone clusters can have 1 or more CKUs, whereas multi-zone clusters, which are spread across three availability zones, require a minimum of 2 CKUs. Zone availability cannot be changed after the cluster is created.
* AWS and Google Cloud support Kafka clusters to 152 CKUs. Azure supports Kafka clusters to 100 CKUs.
Limits per CKU¶
CKUs determine the capacity of your cluster. For a Confluent Cloud cluster, the expected performance for any given workload is dependent on a variety of dimensions, such as message size and number of partitions.
There are two categories of CKU dimensions:
- Dimensions with a fixed limit that cannot be exceeded.
- Dimensions with a more flexible guideline that may be exceeded depending on the overall cluster load.
The recommended guideline for a dimension is calculated for a workload optimized across the dimensions, enabling high levels of CKU utilization as measured by the cluster load metric. You may exceed the recommended guideline for a dimension, and achieve higher performance for that dimension, usually only if your usage of other dimensions is less than the recommended guideline or fixed limit.
Also note that usage patterns across all dimensions affect the workload and you may not achieve the suggested guideline for a particular dimension. For example, if you reach the partition limit, you will not likely reach the maximum CKU throughput guideline.
You should monitor the cluster load metric for your cluster to see how your usage pattern correlates with cluster utilization.
When a cluster’s load metric is high, the cluster may delay new connections and/or throttle clients in an attempt to ensure the cluster remains available. This throttling would register as non-zero values for the producer client produce-throttle-time-max and produce-throttle-time-avg metrics and consumer client fetch-throttle-time-max and fetch-throttle-time-avg metrics.
Use the information in the following tables to determine the minimum number of CKUs to use for a given workload, how to monitor a dimension and suggestions to reduce your use of a particular dimension.
Dimensions with fixed limits¶
The following table lists dimensions that have a fixed maximum limit that cannot be exceeded.
Dimension | Maximum per CKU | Details |
---|---|---|
Storage (pre-replication) | Infinite | Number of bytes retained on the cluster, pre-replication. Dedicated clusters have Infinite Storage, which means there is no maximum size limit for the amount of data that can be stored on the cluster. Available in the Metrics API as You can configure policy settings If you are self-managing Kafka, you can look at how much disk space your cluster is using to understand your storage needs. To reduce usage on this dimension, you can
compress your messages
and reduce your retention settings.
|
Partitions (pre-replication) | 4,500 partitions (100,000 partitions maximum across all CKUs) | Maximum number of partitions that can exist on the cluster at one time, before replication.
All topics that the customer creates as well as internal topics that are automatically created
by Confluent Platform components–such as ksqlDB, Kafka Streams, Connect, and Control Center–count towards the cluster
partition limit. The automatically created topics are prefixed with an underscore ( Available in the Metrics API as Attempts to create additional partitions beyond this limit will fail with an error message. If you are self-managing Kafka, you can look at the To reduce usage on this dimension, you can delete unused topics and create new topics with fewer partitions. You can use the Kafka Admin interface to increase the partition count of an existing topic if the initial partition count is too low. |
Connection attempts | 500 connection attempts per second | Maximum number of new TCP connections to the cluster that can be created in one second. This means successful authentications plus unsuccessful authentication attempts. If you exceed the maximum, connection attempts may be refused. If you are self-managing Kafka, you can look at the rate of change for the
kafka.server:type=socket-server-metrics,listener={listener_name},networkProcessor={#},name=connection-count metric and
the Consumer |
Kafka REST Produce v3 | Max throughput: 50 MBps Max connection requests: up to 300 connection requests per second Max streamed requests: 3000 requests per second |
Client applications can connect over the REST API to Produce records directly to the Confluent Cloud cluster. To learn more, see the Kafka REST concepts overview. The max connection requests limit is shared between Produce and Admin v3. For example, if Produce is running at 100 connection requests per second, Admin can run at approximately 200 connection requests per second maximum. To learn more about the Kafka REST Produce API streaming mode, see the examples and explanation of streaming mode in the concept docs, and the Produce example in the quick start. A streamed request is a single record to be produced to Kafka. Concatenate the records to produce multiple records in the same request. Delivery reports are concatenated in the same order as the records are sent. For more information, see Produce Records. |
Kafka REST Admin v3 | Max connection requests: up to 300 connection requests per second | This limit is shared between Produce and Admin v3. For example, if Produce is running at 100 connection requests per second, Admin can run at approximately 200 connection requests per second maximum. |
Dimensions with a recommended guideline¶
The following table lists dimensions with a recommended guideline.
These dimensions provide guidelines for capacity planning. The ability to fully utilize these dimensions depend on the workload and utilization of other dimensions. See more about measuring load in cluster load metric and for the maximum bandwidth for each cloud provider (AWS, Google Cloud, Azure), are available in Benchmark Your Dedicated Apache Kafka Cluster on Confluent Cloud.
Dimension | Guideline per CKU | Details |
---|---|---|
Ingress | 60 megabytes per second (MBps) | Number of bytes that can be produced to the cluster in one second. Available in the Metrics API as If you are self-managing Kafka, you can look at the producer outgoing-byte-rate metrics and broker kafka.server:type=BrokerTopicMetrics,name=BytesInPerSec metrics to understand your throughput. To reduce usage on this dimension, you can compress your messages.
|
Egress | 180 megabytes per second (MBps) | Number of bytes that can be consumed from the cluster in one second. Available in the the Metrics API as If you are self-managing Kafka, you can look at the consumer incoming-byte-rate metrics and broker kafka.server:type=BrokerTopicMetrics,name=BytesOutPerSec to understand your throughput. To reduce usage on this dimension, you can compress your messages
and ensure each consumer is only consuming from the topics it requires. |
Total client connections | 18,000 connections | Number of TCP connections to the cluster that can be open at one time. Available
in the Metrics API as If you are self-managing Kafka, you can look at the broker kafka.server:type=socket-server-metrics,listener={listener_name},networkProcessor={#},name=connection-count metrics to understand how many connections you are using. This value may not have a 1:1 ratio to connections in Confluent Cloud, depending on the number of brokers, partitions, and applications in your self-managed cluster. How many connections a cluster supports can vary widely based on several factors, including number of producer clients, number of consumer clients, partition keying strategy, produce patterns per client, and consume patterns per client. Confluent derives this guideline from benchmarking that indicates exceeding this number of connections increases produce latency for test clients. However, this doesn’t apply to all workloads. This is why total client connections are a guideline, not a hard limit for Dedicated Kafka clusters. Monitor the impact on cluster load as connection count increases, as this is the final representation of the impact of a given workload or CKU dimension on the cluster’s underlying resources. Consider this guideline a per-CKU guideline. The number of connections tends to increase when you add brokers. In other words, if you significantly exceed the per-CKU guideline, cluster expansion won’t always give your cluster more connection count headroom. |
Requests | 15,000 requests per second | Number of client requests to the cluster in one second. Available in the the Metrics API as If you are self-managing Kafka, you can look at the broker kafka.network:type=RequestMetrics,name=RequestsPerSec,request={Produce FetchConsumer FetchFollower} metrics and client request-rate metrics to understand your request volume. To reduce usage on this dimension, you can adjust producer batching configurations, consumer client batching configurations, and shut down otherwise inactive clients. A high number of requests per second results in increased load on the cluster. |
Dedicated limits per cluster¶
Dedicated clusters use CKUs to govern some dimensions for cluster limits. Other dimensions are simple limits
and do not change as you increase the number of CKUs. In the following table, per CKU
means you must multiply the
CKU limit for that dimension by the number of CKUs you purchased to determine the limit for your cluster.
For more information, see Limits per CKU.
For more information about quotas and limits, see Service Quotas for Confluent Cloud and Kafka topic configurations for all Confluent Cloud cluster types.
Dimension | Capability | Additional details |
---|---|---|
Ingress * | 9,120 | See Dimensions with a recommended guideline. |
Egress * | 27,360 | See Dimensions with a recommended guideline. |
Storage * | Infinite | See Dimensions with fixed limits. |
Partitions * | 100,000 | Depends on number of CKUs, absolute max 100,000. See Dimensions with fixed limits. |
Total client connections * | 2,736,000 | See Dimensions with a recommended guideline. |
Connection attempts * | 76,000 | See Dimensions with fixed limits. |
Requests * | 2,280,000 | See Dimensions with a recommended guideline. |
Message size | Max 20 MB | For message size defaults at the topic level, see Kafka topic configurations for all Confluent Cloud cluster types. |
Client version | Minimum 0.11.0 | None |
Request size | Max 100 MB | None |
Fetch bytes | Max 55 MB | None |
API keys | Default limit 2,000 | You can request an increase. For more information, see Service Quotas for Confluent Cloud. |
Partition creation and deletion | Max 5,000 per 5 minute period | The following occurs when partition creation and deletion rate limit is reached:
|
Connector tasks per Kafka cluster | Max 250 | None |
ACLs | Default limit 10,000 | You can request an increase. For more information, see Service Quotas for Confluent Cloud. |
Kafka REST Produce v3 | Max message size: 20 MB | For Kafka REST Produce v3, only maximum message size is a cluster limit. All other limits for Kafka REST Produce v3 (throughput, connection requests, and streamed requests) are per CKU. See Dimensions with fixed limits. |
* Limit based on a Dedicated Kafka cluster with 152 CKU. For more information, see CKU limits per cluster and Confluent Unit for Kafka.
Dedicated limits per partition¶
You can add CKUs to a Dedicated cluster to meet the capacity for your high traffic workloads. However, the limits shown in this table will not change as you increase the number of CKUs.
The partition capabilities that follow are based on benchmarking and intended as practical guidelines for planning purposes. Performance per partition will vary depending on your individual configuration, and these benchmarks do not guarantee performance.
Dimension | Capability |
---|---|
Ingress per Partition | Max 12 MBps (aggregate producer throughput) |
Egress per Partition | Max 36 MBps (aggregate consumer throughput) |
Storage per Partition | Unlimited |
Storage per Partition for Compacted Topics | Unlimited |
Dedicated provisioning time¶
Most clusters are provisioned in less than two hours. You receive an email when provisioning is complete.
Sometimes, due to cloud provider specific constraints, provisioning can take longer. Please check our status page for any ongoing service disruptions. Contact Confluent Support if provisioning takes longer than 6 hours.
Note that provisioning time is excluded from the Confluent SLA.
Dedicated resizing time¶
Resizing a cluster on average takes about 30-60 minutes per CKU. After you request a Kafka cluster resize, you cannot request another change until the original request completes.
When a cluster is under heavy load or has a high number of partitions to move, resizing can take longer than expected.
During a resize operation, your applications may see leader elections, but otherwise performance will not suffer. Supported Kafka clients will gracefully handle these changes. You will receive an email when the resize operation is complete.
Cluster Linking capabilities¶
Dedicated clusters can be a source or destination of a cluster link, dependent on the networking type and the other cluster involved. To learn more, see Supported cluster types in the Cluster Linking documentation.