Modifying a replication group - Amazon ElastiCache for Redis
Using the Amazon Web Services Management ConsoleUsing the Amazon CLIUsing the ElastiCache API
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Modifying a replication group

Important Constraints

  • Currently, ElastiCache supports limited modifications of a Redis (cluster mode enabled) replication group, for example changing the engine version, using the API operation ModifyReplicationGroup (CLI: modify-replication-group). You can modify the number of shards (node groups) in a Redis (cluster mode enabled) cluster with the API operation ModifyReplicationGroupShardConfiguration (CLI: modify-replication-group-shard-configuration). For more information, see Scaling clusters in Redis (Cluster Mode Enabled).

    Other modifications to a Redis (cluster mode enabled) cluster require that you create a cluster with the new cluster incorporating the changes.

  • You can upgrade Redis (cluster mode disabled) and Redis (cluster mode enabled) clusters and replication groups to newer engine versions. However, you can't downgrade to earlier engine versions except by deleting the existing cluster or replication group and creating it again. For more information, see Engine versions and upgrading .

  • You can upgrade an existing ElastiCache for Redis cluster that uses cluster mode disabled to use cluster mode enabled, using the console, ModifyReplicationGroup API or the modify-replication-group CLI command, as shown in the example below. Or you can follow the steps at Modifying cluster mode.

You can modify a Redis (cluster mode disabled) cluster's settings using the ElastiCache console, the Amazon CLI, or the ElastiCache API. Currently, ElastiCache supports a limited number of modifications on a Redis (cluster mode enabled) replication group. Other modifications require you create a backup of the current replication group then using that backup to seed a new Redis (cluster mode enabled) replication group.

Using the Amazon Web Services Management Console

To modify a Redis (cluster mode disabled) cluster, see Modifying an ElastiCache cluster.

Using the Amazon CLI

The following are Amazon CLI examples of the modify-replication-group command. You can use the same command to make other modifications to a replication group.

Enable Multi-AZ on an existing Redis replication group:

For Linux, OS X, or Unix:

aws elasticache modify-replication-group \
   --replication-group-id myReplGroup \
   --multi-az-enabled = true

For Windows:

aws elasticache modify-replication-group ^
   --replication-group-id myReplGroup ^
   --multi-az-enabled

Modify cluster mode from disabled to enabled:

To modify cluster mode from disabled to enabled, you must first set the cluster mode to compatible. Compatible mode allows your Redis clients to connect using both cluster mode enabled and cluster mode disabled. After you migrate all Redis clients to use cluster mode enabled, you can then complete cluster mode configuration and set the cluster mode to enabled.

For Linux, OS X, or Unix:

Set to cluster mode to compatible.

aws elasticache modify-replication-group \
   --replication-group-id myReplGroup \
   --cache-parameter-group-name myParameterGroupName \
   --cluster-mode compatible

Set to cluster mode to enabled.

aws elasticache modify-replication-group \
   --replication-group-id myReplGroup \
   --cluster-mode enabled

For Windows:

Set to cluster mode to compatible.

aws elasticache modify-replication-group ^
   --replication-group-id myReplGroup ^
   --cache-parameter-group-name myParameterGroupName ^
   --cluster-mode compatible

Set to cluster mode to enabled.

aws elasticache modify-replication-group ^
   --replication-group-id myReplGroup ^
   --cluster-mode enabled

For more information on the Amazon CLI modify-replication-group command, see modify-replication-group or Modifying cluster mode in the ElastiCache for Redis User Guide.

Using the ElastiCache API

The following ElastiCache API operation enables Multi-AZ on an existing Redis replication group. You can use the same operation to make other modifications to a replication group.

https://elasticache.us-west-2.amazonaws.com/
   ?Action=ModifyReplicationGroup
   &AutomaticFailoverEnabled=true  
   &Mutli-AZEnabled=true  
   &ReplicationGroupId=myReplGroup
   &SignatureVersion=4
   &SignatureMethod=HmacSHA256
   &Timestamp=20141201T220302Z
   &Version=2014-12-01
   &X-Amz-Algorithm=&AWS;4-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 the ElastiCache API ModifyReplicationGroup operation, see ModifyReplicationGroup.