<p>Creates a Redis (cluster mode disabled) or a Redis (cluster mode enabled) replication group.</p> <p>This API can be used to create a standalone regional replication group or a secondary replication group associated with a Global datastore.</p> <p>A Redis (cluster mode disabled) replication group is a collection of clusters, where one of the clusters is a read/write primary and the others are read-only replicas. Writes to the primary are asynchronously propagated to the replicas.</p> <p>A Redis cluster-mode enabled cluster is comprised of from 1 to 90 shards (API/CLI: node groups). Each shard has a primary node and up to 5 read-only replica nodes. The configuration can range from 90 shards and 0 replicas to 15 shards and 5 replicas, which is the maximum number or replicas allowed. </p> <p>The node or shard limit can be increased to a maximum of 500 per cluster if the Redis engine version is 5.0.6 or higher. For example, you can choose to configure a 500 node cluster that ranges between 83 shards (one primary and 5 replicas per shard) and 500 shards (single primary and no replicas). Make sure there are enough available IP addresses to accommodate the increase. Common pitfalls include the subnets in the subnet group have too small a CIDR range or the subnets are shared and heavily used by other clusters. For more information, see <a href="https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/SubnetGroups.Creating.html">Creating a Subnet Group</a>. For versions below 5.0.6, the limit is 250 per cluster.</p> <p>To request a limit increase, see <a href="https://docs.aws.amazon.com/general/latest/gr/aws_service_limits.html">Amazon Service Limits</a> and choose the limit type <b>Nodes per cluster per instance type</b>. </p> <p>When a Redis (cluster mode disabled) replication group has been successfully created, you can add one or more read replicas to it, up to a total of 5 read replicas. If you need to increase or decrease the number of node groups (console: shards), you can avail yourself of ElastiCache for Redis' scaling. For more information, see <a href="https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Scaling.html">Scaling ElastiCache for Redis Clusters</a> in the <i>ElastiCache User Guide</i>.</p> <note> <p>This operation is valid for Redis only.</p> </note>

{
  "success": true,
  "data": {
    "id": "abc123",
    "created_at": "2025-01-01T00:00:00Z"
  }
}

{
  "success": false,
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid request parameters"
  }
}