Amazon ElastiCache for Redis
ElastiCache for Redis User Guide (API Version 2015-02-02)

Promoting a Read Replica to Primary, for Redis (cluster mode disabled) Replication Groups

Information in the following topic applies to only Redis (cluster mode disabled) replication groups.

You can promote a Redis (cluster mode disabled) read replica to primary using the AWS Management Console, the AWS CLI, or the ElastiCache API. You can't promote a read replica to primary while Multi-AZ with Automatic Failover is enabled on the Redis (cluster mode disabled) replication group. To promote a Redis (cluster mode disabled) replica to primary on a Multi-AZ enabled replication group, do the following:

  1. Modify the replication group to disable Multi-AZ (doing this doesn't require that all your clusters be in the same Availability Zone). For more information, see Modifying a Replication Group.

  2. Promote the read replica to primary.

  3. Modify the replication group to re-enable Multi-AZ.

Multi-AZ with Automatic Failover is not available on replication groups running Redis 2.6.13 or earlier.

Using the AWS Management Console

The following procedure uses the console to promote a replica node to primary.

To promote a read replica to primary (console)

  1. Sign in to the AWS Management Console and open the ElastiCache console at https://console.aws.amazon.com/elasticache/.

  2. If the replica you want to promote is a member of a Redis (cluster mode disabled) replication group where Multi-AZ is enabled, modify the replication group to disable Multi-AZ before you proceed. For more information, see Modifying a Replication Group.

  3. Choose Redis, then from the list of clusters, choose the replication group that you want to modify. This replication group must be running the "Redis" engine, not the "Clustered Redis" engine, and must have two or more nodes.

  4. From the list of nodes, choose the replica node you want to promote to primary, then for Actions, choose Promote.

  5. In the Promote Read Replica dialog box, do the following:

    1. For Apply Immediately, choose Yes to promote the read replica immediately, or No to promote it at the cluster's next maintenance window.

    2. Choose Promote to promote the read replica or Cancel to cancel the operation.

  6. If the cluster was Multi-AZ enabled before you began the promotion process, wait until the replication group's status is available, then modify the cluster to re-enable Multi-AZ. For more information, see Modifying a Replication Group.

Using the AWS CLI

You can't promote a read replica to primary if the replication group is Multi-AZ enabled. If the replica that you want to promote is a member of a replication group where Multi-AZ is enabled, you must modify the replication group to disable Multi-AZ before you proceed. Doing this doesn't require that all your clusters be in the same Availability Zone. For more information on modifying a replication group, see Modifying a Replication Group.

The following AWS CLI command modifies the replication group sample-repl-group, making the read replica my-replica-1 the primary in the replication group.

For Linux, macOS, or Unix:

aws elasticache modify-replication-group \ --replication-group-id sample-repl-group \ --primary-cluster-id my-replica-1

For Windows:

aws elasticache modify-replication-group ^ --replication-group-id sample-repl-group ^ --primary-cluster-id my-replica-1

For more information on modifying a replication group, see modify-replication-group in the Amazon ElastiCache Command Line Reference.

Using the ElastiCache API

You can't promote a read replica to primary if the replication group is Multi-AZ enabled. If the replica that you want to promote is a member of a replication group where Multi-AZ is enabled, you must modify the replication group to disable Multi-AZ before you proceed. Doing this doesn't require that all your clusters be in the same Availability Zone. For more information on modifying a replication group, see Modifying a Replication Group.

The following ElastiCache API action modifies the replication group myReplGroup, making the read replica myReplica-1 the primary in the replication group.

https://elasticache.us-west-2.amazonaws.com/ ?Action=ModifyReplicationGroup &ReplicationGroupId=myReplGroup &PrimaryClusterId=myReplica-1 &Version=2014-12-01 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20141201T220302Z &X-Amz-Algorithm=AWS4-HMAC-SHA256 &X-Amz-Date=20141201T220302Z &X-Amz-SignedHeaders=Host &X-Amz-Expires=20141201T220302Z &X-Amz-Credential=<credential> &X-Amz-Signature=<signature>

For more information on modifying a replication group, see ModifyReplicationGroup in the Amazon ElastiCache API Reference.