:_mod-docs-content-type: CONCEPT

// Module included in the following assemblies:
//
// assembly-config.adoc

[id='con-config-kafka-connect-multiple-instances-{context}']
= Running multiple Kafka Connect instances

[role="_abstract"]
When running multiple Kafka Connect instances against the same Kafka cluster, each instance must use a unique cluster group ID and internal topic names.
If these settings are shared, the instances form a single logical cluster and attempt to use the same internal topics, which can lead to unexpected errors.

The following example shows the properties that must be unique for each Kafka Connect instance:

[source,yaml,subs="attributes+"]
----
apiVersion: {KafkaConnectApiVersion}
kind: KafkaConnect
metadata:
  name: my-connect
spec:
  groupId: my-connect-cluster
  configStorageTopic: my-connect-cluster-configs
  offsetStorageTopic: my-connect-cluster-offsets
  statusStorageTopic: my-connect-cluster-status
  # ...
----
* `spec.groupId` specifies the Kafka Connect cluster group ID used within Kafka.
* `spec.configStorageTopic` specifies the Kafka topic that stores connector and task configurations.
* `spec.offsetStorageTopic` specifies the Kafka topic that stores connector offsets.
* `spec.statusStorageTopic` specifies the Kafka topic that stores connector and task status updates.

Each Kafka Connect instance that targets the same Kafka cluster must use unique values for these properties.

This requirement applies across all Kafka Connect–based deployments, including Kafka Connect and MirrorMaker 2 instances that target the same Kafka cluster.

If multiple instances use the same cluster group ID and internal topics, they form a single logical cluster and attempt to share internal state.
This can cause unexpected errors, so you must configure unique values for these properties for each instance.