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

Creating a Redis (cluster mode enabled) Cluster (Console)

If you are running Redis 3.2.4 or later, you can create a Redis (cluster mode enabled) cluster. Redis (cluster mode enabled) clusters support partitioning your data across 1 to 15 shards (API/CLI: node groups) but with some limitations (currently). For a comparison of Redis (cluster mode disabled) and the two flavors of Redis (cluster mode enabled), see Choosing an Engine: Memcached, Redis (cluster mode disabled), or Redis (cluster mode enabled).

You can create a Redis (cluster mode enabled) cluster (API/CLI: replication group) using the ElastiCache management console, the AWS CLI for ElastiCache, and the ElastiCache API.

To create a Redis (cluster mode enabled) cluster using the ElastiCache console

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

  2. Choose Get Started Now.

    If you already have an available cluster, choose Redis from the left navigation pane.

  3. Choose Create.

  4. For Cluster engine, choose Redis, and then choose Cluster Mode enabled (Scale Out). These selections create a Redis (cluster mode enabled) cluster that looks something like this.

    Image: Redis (cluster mode enabled) cluster created with replication and data partitioning

    Redis (cluster mode enabled) cluster created with replication and data partitioning

  5. Complete the Redis (cluster mode enabled) settings section.

    1. In the Name box, type a name for your Cluster.

      Cluster naming constraints

      • Must contain from 1 to 20 alphanumeric characters or hyphens.

      • Must begin with a letter.

      • Cannot contain two consecutive hyphens.

      • Cannot end with a hyphen.

    2. In the Description box, type in a description of this cluster.

    3. For Engine version compatibility, choose 3.2.4.

    4. In the Port box, accept the default port, 6379. If you have a reason to use a different port, type the port number.

    5. For Parameter group, choose the parameter group you want to use with this cluster, or choose Create new to create a new parameter group to use with this cluster.

      Parameter groups control the run-time parameters of your cluster. For more information on parameter groups, see Redis Specific Parameters and Creating a Parameter Group.

    6. For Node type, choose the down arrow ( ). In the Change node type dialog box, choose the Instance family of the node type you want, choose the node type you want to use for this cluster, and then choose Save.

      For more information, see Choosing Your Node Size.

    7. For Number of shards, choose the number of shards (partitions) you want for this Redis (cluster mode enabled) cluster.

      In Redis (cluster mode enabled) once you create the cluster the number of shards is fixed and cannot be changed. If you find you need more or fewer shards, you must create a new cluster with the new number of shards. For more information, see Restoring From a Backup with Cluster Resizing.

    8. For Replicas per shard, choose the number of read replica nodes you want in each shard.

      The following restrictions exist for Redis (cluster mode enabled).

      • The number of replicas is the same for each shard when creating the cluster using the console.

         

      • The number of read replicas per shard is fixed and cannot be changed. If you find you need more or fewer replicas per shard (API/CLI: node group), you must create a new cluster with the new number of replicas. For more information, see Seeding a New Cluster with an Externally Created Backup (Redis).

    9. For Subnet group, choose the subnet you want to apply to this cluster.

      For more information, see Subnets and Subnet Groups.

  6. Click Advanced Redis settings and complete the section.

    1. For Slots and keyspaces, choose how you want your keys distributed over your shards (partitions). There are 16,384 keys to be distributed (numbered 0 through 16,383).

      • Equal distribution – ElastiCache distributes your keyspace as equally as possible over your shards.

         

      • Custom distribution – you specify the range of keys for each shard in the table below Availability zone(s).

    2. Choose how you want the Availability zone(s) chosen for this cluster. You have two options.

      • No preference – ElastiCache will choose the availability zone.

         

      • Specify availability zones – You specify the availability zone for each cluster.

        If you chose to specify the availability zones, for each cluster in each shard, choose the availability zone from the list.

      For more information, see Choosing Regions and Availability Zones.

      Image: Specifying Keyspaces and Availability Zones

      Specifying Keyspaces and Availability Zones

    3. For Security groups, choose the security groups you want for this cluster.

      For more information, see ElastiCache and Security Groups.

    4. If you are going to seed your cluster with data from a .RDB file, in the Seed RDB file S3 location box, enter the S3 location of the .RDB file.

      For more information, see Seeding a New Cluster with an Externally Created Backup (Redis).

      For Redis (cluster mode enabled) you must have a separate .RDB file for each node group.

    5. If you want regularly scheduled automatic backups, choose Enable automatic backups the type the number of days you want each automatic backup retained before it is automatically deleted. If you don't want regularly scheduled automatic backups, clear the Enable automatic backups check box. In either case, you always have the option to create manual backups.

      For more information on Redis backup and restore, see ElastiCache Backup and Restore (Redis).

    6. The Maintenance window is the time, generally an hour in length, each week when ElastiCache schedules system maintenance for your cluster. You can allow ElastiCache to choose the day and time for your maintenance window (No preference), or you can choose the day, time, and duration yourself (Specify maintenance window). If you choose Specify maintenance window from the lists, choose the Start day, Start time, and Duration (in hours) for your maintenance window. All times are UCT times.

      For more information, see Maintenance Window.

    7. For Notifications, choose an existing Amazon Simple Notification Service (Amazon SNS) topic, or choose Manual ARN input and type in the topic's Amazon Resource Name (ARN). Amazon SNS allows you to push notifications to Internet-connected smart devices. The default is to disable notifications. For more information, see https://aws.amazon.com/sns/.

  7. Review all your entries and choices, then go back and make any needed corrections. When everything is just the way you want it, choose Create cluster to launch your cluster, or Cancel to cancel the operation.

To create the equivalent using the ElastiCache API or AWS CLI instead of the ElastiCache console, see:

As soon as your cluster's status is available, you can grant EC2 access to it, connect to it, and begin using it. For more information, see Step 4: Authorize Access and Step 5: Connect to a Cluster's Node.

Important

As soon as your cluster becomes available, you're billed for each hour or partial hour that the cluster is active, even if you're not actively using it. To stop incurring charges for this cluster, you must delete it. See Deleting a Cluster.