Active-Active databases

Content related to Active-Active Redis Enterprise databases for Kubernetes.

On Kubernetes, Redis Enterprise Active-Active databases provide read and write access to the same dataset from different Kubernetes clusters.

Active-Active setup methods

There are two methods for creating an Active-Active database with Redis Enterprise for Kubernetes:

• The RedisEnterpriseActiveActiveDatabase (REAADB) custom resource is available for versions 6.4.2 and later.
• The crdb-cli method is available for versions 6.4.2 or earlier.

We recommend creating new Active-Active databases using the RedisEnterpriseActiveActiveDatabase (REAADB) custom resource. This allows you to manage your Active-Active database with the operator and ensures you have the latest features and functionality.

Active-Active controller method

Versions 6.4.2-6 or later fully support the Active-Active controller. Some of these features were available as a preview in 6.4.2-4 and 6.4.2-5. Please upgrade to 6.4.2-6 for the full set of general availability features and bug fixes.

This setup method includes the following steps:

1. Gather REC credentials and prepare participating clusters.
2. Create RedisEnterpriseRemoteCluster (RERC) resources.
3. Create RedisEnterpriseActiveActiveDatabase (REAADB) resource.

crdb-cli method

For versions 6.4.2 or earlier, this Active-Active setup method includes the following steps:

1. Install and configure an ingress.
2. Gather configuration details.
3. Add the ActiveActive field to the REC spec.
4. Create the database with the crdb-cli tool.

Redis Enterprise Active-Active controller for Kubernetes

Active-Active databases give you read-and-write access to Redis Enterprise clusters (REC) in different Kubernetes clusters or namespaces. Active-Active deployments managed by the Redis Enterprise operator require two additional custom resources: Redis Enterprise Active-Active database (REAADB) and Redis Enterprise remote cluster (RERC).

To create an Active-Active Redis Enterprise deployment for Kubernetes with these new features, first prepare participating clusters then create an Active-Active database.

Preview versions

If you are using a preview version of these features (operator version 6.4.2-4 or 6.4.2-5), you'll need to enable the Active-Active controller with the following steps. You need to do this only once per cluster. We recommend using the fully supported 6.4.2-6 version.

1. Download the custom resource definitions (CRDs) for the most recent release (6.4.2-4) from redis-enterprise-k8s-docs Github.

2. Apply the new CRDs for the Redis Enterprise Active-Active database (REAADB) and Redis Enterprise remote cluster (RERC) to install those controllers.

   kubectl apply -f crds/reaadb_crd.yaml
   kubectl apply -f crds/rerc_crd.yaml
   

3. Enable the Active-Active and remote cluster controllers on the operator ConfigMap.

   kubectl patch cm  operator-environment-config --type merge --patch "{\"data\": \
   {\"ACTIVE_ACTIVE_DATABASE_CONTROLLER_ENABLED\":\"true\", \
   \"REMOTE_CLUSTER_CONTROLLER_ENABLED\":\"true\"}}"
   

REAADB custom resource

Redis Enterprise Active-Active database (REAADB) contains a link to the RERC for each participating cluster, and provides configuration and status to the management plane.

For a full list of fields and options, see the REAADB API reference.

RERC custom resource

Redis Enterprise remote cluster (RERC) custom resource contains configuration details for all the participating clusters.

For a full list of fields and options, see the RERC API reference.

Limitations

• Existing Redis databases cannot be migrated to a REAADB. (DOC-3594)
• Admission is not blocking REAADB with shardCount which exceeds license quota. (RED-96301) Workaround: Fix the problems with the REAADB and reapply.
• The <rec-name>/<rec-namespace> value must be unique for each RERC resource. (RED-96302)
• Only global database options are supported, no support for specifying configuration per location.
• No support for migration from old (crdb-cli) Active-Active database method to new Active-Active controller.
• No support for REAADB with participating clusters co-located within the same Kubernetes cluster, except for a single designated local participating cluster.

More info

For more general information about Active-Active, see the Redis Enterprise Software docs.