# Creating a Valkey or Redis OSS replication group
You have the following options for creating a cluster with replica nodes. One applies when you already have an available Valkey or Redis OSS (cluster mode disabled) cluster not associated with any cluster that has replicas to use as the primary node. The other applies when you need to create a primary node with the cluster and read replicas. Currently, a Valkey or Redis OSS (cluster mode enabled) cluster must be created from scratch.
**Option 1: [Creating a replication group using an existing cluster](Replication.CreatingReplGroup.ExistingCluster.md)**
Use this option to leverage an existing single-node Valkey or Redis OSS (cluster mode disabled) cluster. You specify this existing node as the primary node in the new cluster, and then individually add 1 to 5 read replicas to the cluster. If the existing cluster is active, read replicas synchronize with it as they are created. See [Creating a replication group using an existing cluster](Replication.CreatingReplGroup.ExistingCluster.md).
You cannot create a Valkey or Redis OSS (cluster mode enabled) cluster using an existing cluster. To create a Valkey or Redis OSS (cluster mode enabled) cluster (API/CLI: replication group) using the ElastiCache console, see [Creating a Valkey or Redis OSS (cluster mode enabled) cluster (Console)](Clusters.Create.md#Clusters.Create.CON.RedisCluster).
**Option 2: [Creating a Valkey or Redis OSS replication group from scratch](Replication.CreatingReplGroup.NoExistingCluster.md)**
Use this option if you don't already have an available Valkey or Redis OSS (cluster mode disabled) cluster to use as the cluster's primary node, or if you want to create a Valkey or Redis OSS (cluster mode enabled) cluster. See [Creating a Valkey or Redis OSS replication group from scratch](Replication.CreatingReplGroup.NoExistingCluster.md).
# Creating a replication group using an existing cluster
The following procedure adds a replication group to your Valkey or Redis OSS (cluster mode disabled) single-node cluster, which is necessary in order to upgrade your cluster to the latest version of Valkey. This is an in-place procedure that involves zero downtime and zero data loss. When you create a replication group for your single-node cluster, the cluster's node becomes the primary node in the new cluster. If you do not have a Valkey or Redis OSS (cluster mode disabled) cluster that you can use as the new cluster's primary, see [Creating a Valkey or Redis OSS replication group from scratch](Replication.CreatingReplGroup.NoExistingCluster.md).
An available cluster is an existing single-node Valkey or Redis OSS cluster. Currently, Valkey or Redis OSS (cluster mode enabled) does not support creating a cluster with replicas using an available single-node cluster. If you want to create a Valkey or Redis OSS (cluster mode enabled) cluster, see [Creating a Valkey or Redis OSS (Cluster Mode Enabled) cluster (Console)](Replication.CreatingReplGroup.NoExistingCluster.Cluster.md#Replication.CreatingReplGroup.NoExistingCluster.Cluster.CON).
## Creating a replication group using an existing cluster (Console)
See the topic [Using the ElastiCache AWS Management Console](Clusters.AddNode.md#Clusters.AddNode.CON).
## Creating a replication group using an available Valkey or Redis OSS cluster (AWS CLI)
There are two steps to creating a replication group with read replicas when using an available Valkey or Redis OSS Cache Cluster for the primary when using the AWS CLI.
When using the AWS CLI you create a replication group specifying the available standalone node as the cluster's primary node, `--primary-cluster-id` and the number of nodes you want in the cluster using the CLI command, `create-replication-group`. Include the following parameters.
**--replication-group-id**
The name of the replication group you are creating. The value of this parameter is used as the basis for the names of the added nodes with a sequential 3-digit number added to the end of the `--replication-group-id`. For example, `sample-repl-group-001`.
Valkey or Redis OSS (cluster mode disabled) replication group naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**--replication-group-description**
Description of the replication group.
**--num-node-groups**
The number of nodes you want in this cluster. This value includes the primary node. This parameter has a maximum value of six.
**--primary-cluster-id**
The name of the available Valkey or Redis OSS (cluster mode disabled) cluster's node that you want to be the primary node in this replication group.
The following command creates the replication group `sample-repl-group` using the available Valkey or Redis OSS (cluster mode disabled) cluster `redis01` as the replication group's primary node. It creates 2 new nodes which are read replicas. The settings of `redis01` (that is, parameter group, security group, node type, engine version, and so on.) will be applied to all nodes in the replication group.
For Linux, macOS, or Unix:
```
aws elasticache create-replication-group \
--replication-group-id sample-repl-group \
--replication-group-description "demo cluster with replicas" \
--num-cache-clusters 3 \
--primary-cluster-id redis01
```
For Windows:
```
aws elasticache create-replication-group ^
--replication-group-id sample-repl-group ^
--replication-group-description "demo cluster with replicas" ^
--num-cache-clusters 3 ^
--primary-cluster-id redis01
```
For additional information and parameters you might want to use, see the AWS CLI topic [create-replication-group](https://docs.aws.amazon.com/cli/latest/reference/elasticache/create-replication-group.html).
**Next, add read replicas to the replication group**
After the replication group is created, add one to five read replicas to it using the `create-cache-cluster` command, being sure to include the following parameters.
**--cache-cluster-id**
The name of the cluster you are adding to the replication group.
Cluster naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**--replication-group-id**
The name of the replication group to which you are adding this cluster.
Repeat this command for each read replica you want to add to the replication group, changing only the value of the `--cache-cluster-id` parameter.
**Note**
Remember, a replication group cannot have more than five read replicas. Attempting to add a read replica to a replication group that already has five read replicas causes the operation to fail.
The following code adds the read replica `my-replica01` to the replication group `sample-repl-group`. The settings of the primary cluster–parameter group, security group, node type, and so on.–will be applied to nodes as they are added to the replication group.
For Linux, macOS, or Unix:
```
aws elasticache create-cache-cluster \
--cache-cluster-id my-replica01 \
--replication-group-id sample-repl-group
```
For Windows:
```
aws elasticache create-cache-cluster ^
--cache-cluster-id my-replica01 ^
--replication-group-id sample-repl-group
```
Output from this command will look something like this.
```
{
"ReplicationGroup": {
"Status": "creating",
"Description": "demo cluster with replicas",
"ClusterEnabled": false,
"ReplicationGroupId": "sample-repl-group",
"SnapshotRetentionLimit": 1,
"AutomaticFailover": "disabled",
"SnapshotWindow": "00:00-01:00",
"SnapshottingClusterId": "redis01",
"MemberClusters": [
"sample-repl-group-001",
"sample-repl-group-002",
"redis01"
],
"CacheNodeType": "cache.m4.large",
"DataTiering": "disabled",
"PendingModifiedValues": {}
}
}
```
For additional information, see the AWS CLI topics:
+ [create-replication-group](https://docs.aws.amazon.com/cli/latest/reference/elasticache/create-replication-group.html)
+ [modify-replication-group](https://docs.aws.amazon.com/cli/latest/reference/elasticache/modify-replication-group.html)
## Adding replicas to a standalone Valkey or Redis OSS (Cluster Mode Disabled) cluster (ElastiCache API)
When using the ElastiCache API, you create a replication group specifying the available standalone node as the cluster's primary node, `PrimaryClusterId` and the number of nodes you want in the cluster using the CLI command, `CreateReplicationGroup`. Include the following parameters.
**ReplicationGroupId**
The name of the replication group you are creating. The value of this parameter is used as the basis for the names of the added nodes with a sequential 3-digit number added to the end of the `ReplicationGroupId`. For example, `sample-repl-group-001`.
Valkey or Redis OSS (cluster mode disabled) replication group naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**ReplicationGroupDescription**
Description of the cluster with replicas.
**NumCacheClusters**
The number of nodes you want in this cluster. This value includes the primary node. This parameter has a maximum value of six.
**PrimaryClusterId**
The name of the available Valkey or Redis OSS (cluster mode disabled) cluster that you want to be the primary node in this cluster.
The following command creates the cluster with replicas `sample-repl-group` using the available Valkey or Redis OSS (cluster mode disabled) cluster `redis01` as the replication group's primary node. It creates 2 new nodes which are read replicas. The settings of `redis01` (that is, parameter group, security group, node type, engine version, and so on.) will be applied to all nodes in the replication group.
```
https://elasticache.us-west-2.amazonaws.com/
?Action=CreateReplicationGroup
&Engine=redis
&EngineVersion=6.0
&ReplicationGroupDescription=Demo%20cluster%20with%20replicas
&ReplicationGroupId=sample-repl-group
&PrimaryClusterId=redis01
&Version=2015-02-02
&SignatureVersion=4
&SignatureMethod=HmacSHA256
&Timestamp=20150202T192317Z
&X-Amz-Credential=
```
For additional information, see the ElastiCache APL topics:
+ [CreateReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateReplicationGroup.html)
+ [ModifyReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_ModifyReplicationGroup.html)
**Next, add read replicas to the replication group**
After the replication group is created, add one to five read replicas to it using the `CreateCacheCluster` operation, being sure to include the following parameters.
**CacheClusterId**
The name of the cluster you are adding to the replication group.
Cluster naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**ReplicationGroupId**
The name of the replication group to which you are adding this cluster.
Repeat this operation for each read replica you want to add to the replication group, changing only the value of the `CacheClusterId` parameter.
The following code adds the read replica `myReplica01` to the replication group `myReplGroup` The settings of the primary cluster–parameter group, security group, node type, and so on.–will be applied to nodes as they are added to the replication group.
```
https://elasticache.us-west-2.amazonaws.com/
?Action=CreateCacheCluster
&CacheClusterId=myReplica01
&ReplicationGroupId=myReplGroup
&SignatureMethod=HmacSHA256
&SignatureVersion=4
&Version=2015-02-02
&X-Amz-Algorithm=&AWS;4-HMAC-SHA256
&X-Amz-Credential=[your-access-key-id]/20150202/us-west-2/elasticache/aws4_request
&X-Amz-Date=20150202T170651Z
&X-Amz-SignedHeaders=content-type;host;user-agent;x-amz-content-sha256;x-amz-date
&X-Amz-Signature=[signature-value]
```
For additional information and parameters you might want to use, see the ElastiCache API topic [CreateCacheCluster](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateCacheCluster.html).
# Creating a Valkey or Redis OSS replication group from scratch
Following, you can find how to create a Valkey or Redis OSS replication group without using an existing Valkey or Redis OSS cluster as the primary. You can create a Valkey or Redis OSS (cluster mode disabled) or Valkey or Redis OSS (cluster mode enabled) replication group from scratch using the ElastiCache console, the AWS CLI, or the ElastiCache API.
Before you continue, decide whether you want to create a Valkey or Redis OSS (cluster mode disabled) or a Valkey or Redis OSS (cluster mode enabled) replication group. For guidance in deciding, see [Replication: Valkey and Redis OSS Cluster Mode Disabled vs. Enabled](Replication.Redis-RedisCluster.md).
**Topics**
+ [Creating a Valkey or Redis OSS (Cluster Mode Disabled) replication group from scratch](Replication.CreatingReplGroup.NoExistingCluster.Classic.md)
+ [Creating a replication group in Valkey or Redis OSS (Cluster Mode Enabled) from scratch](Replication.CreatingReplGroup.NoExistingCluster.Cluster.md)
# Creating a Valkey or Redis OSS (Cluster Mode Disabled) replication group from scratch
You can create a Valkey or Redis OSS (cluster mode disabled) replication group from scratch using the ElastiCache console, the AWS CLI, or the ElastiCache API. A Valkey or Redis OSS (cluster mode disabled) replication group always has one node group, a primary cluster, and up to five read replicas. Valkey or Redis OSS (cluster mode disabled) replication groups don't support partitioning your data.
**Note**
The node/shard limit can be increased to a maximum of 500 per cluster. To request a limit increase, see [AWS Service Limits](https://docs.aws.amazon.com/general/latest/gr/aws_service_limits.html) and include the instance type in the request.
To create a Valkey or Redis OSS (cluster mode disabled) replication group from scratch, take one of the following approaches:
## Creating a Valkey or Redis OSS (Cluster Mode Disabled) replication group from scratch (AWS CLI)
The following procedure creates a Valkey or Redis OSS (cluster mode disabled) replication group using the AWS CLI.
When you create a Valkey or Redis OSS (cluster mode disabled) replication group from scratch, you create the replication group and all its nodes with a single call to the AWS CLI `create-replication-group` command. Include the following parameters.
**--replication-group-id**
The name of the replication group you are creating.
Valkey or Redis OSS (cluster mode disabled) replication group naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**--replication-group-description**
Description of the replication group.
**--num-cache-clusters**
The number of nodes you want created with this replication group, primary and read replicas combined.
If you enable Multi-AZ (`--automatic-failover-enabled`), the value of `--num-cache-clusters` must be at least 2.
**--cache-node-type**
The node type for each node in the replication group.
ElastiCache supports the following node types. Generally speaking, the current generation types provide more memory and computational power at lower cost when compared to their equivalent previous generation counterparts.
For more information on performance details for each node type, see [Amazon EC2 Instance Types](https://aws.amazon.com/ec2/instance-types/).
**--data-tiering-enabled**
Set this parameter if you are using an r6gd node type. If you don't want data tiering, set `--no-data-tiering-enabled`. For more information, see [Data tiering in ElastiCache](data-tiering.md).
**--cache-parameter-group**
Specify a parameter group that corresponds to your engine version. If you are running Redis OSS 3.2.4 or later, specify the `default.redis3.2` parameter group or a parameter group derived from `default.redis3.2` to create a Valkey or Redis OSS (cluster mode disabled) replication group. For more information, see [Valkey and Redis OSS parameters](ParameterGroups.Engine.md#ParameterGroups.Redis).
**--network-type**
Either `ipv4`, `ipv6` or `dual-stack`. If you choose dual-stack, you must set the `--IpDiscovery` parameter to either `ipv4` or `ipv6`.
**--engine**
redis
**--engine-version**
To have the richest set of features, choose the latest engine version.
The names of the nodes will be derived from the replication group name by postpending `-00`*\$1* to the replication group name. For example, using the replication group name `myReplGroup`, the name for the primary will be `myReplGroup-001` and the read replicas `myReplGroup-002` through `myReplGroup-006`.
If you want to enable in-transit or at-rest encryption on this replication group, add either or both of the `--transit-encryption-enabled` or `--at-rest-encryption-enabled` parameters and meet the following conditions.
+ Your replication group must be running Redis OSS version 3.2.6 or 4.0.10.
+ The replication group must be created in an Amazon VPC.
+ You must also include the parameter `--cache-subnet-group`.
+ You must also include the parameter `--auth-token` with the customer specified string value for your AUTH token (password) needed to perform operations on this replication group.
The following operation creates a Valkey or Redis OSS (cluster mode disabled) replication group `sample-repl-group` with three nodes, a primary and two replicas.
For Linux, macOS, or Unix:
```
aws elasticache create-replication-group \
--replication-group-id sample-repl-group \
--replication-group-description "Demo cluster with replicas" \
--num-cache-clusters 3 \
--cache-node-type cache.m4.large \
--engine redis
```
For Windows:
```
aws elasticache create-replication-group ^
--replication-group-id sample-repl-group ^
--replication-group-description "Demo cluster with replicas" ^
--num-cache-clusters 3 ^
--cache-node-type cache.m4.large ^
--engine redis
```
Output from the this command is something like this.
```
{
"ReplicationGroup": {
"Status": "creating",
"Description": "Demo cluster with replicas",
"ClusterEnabled": false,
"ReplicationGroupId": "sample-repl-group",
"SnapshotRetentionLimit": 0,
"AutomaticFailover": "disabled",
"SnapshotWindow": "01:30-02:30",
"MemberClusters": [
"sample-repl-group-001",
"sample-repl-group-002",
"sample-repl-group-003"
],
"CacheNodeType": "cache.m4.large",
"DataTiering": "disabled",
"PendingModifiedValues": {}
}
}
```
For additional information and parameters you might want to use, see the AWS CLI topic [create-replication-group](https://docs.aws.amazon.com/cli/latest/reference/elasticache/create-replication-group.html).
## Creating a Valkey or Redis OSS (cluster mode disabled) replication group from scratch (ElastiCache API)
The following procedure creates a Valkey or Redis OSS (cluster mode disabled) replication group using the ElastiCache API.
When you create a Valkey or Redis OSS (cluster mode disabled) replication group from scratch, you create the replication group and all its nodes with a single call to the ElastiCache API `CreateReplicationGroup` operation. Include the following parameters.
**ReplicationGroupId**
The name of the replication group you are creating.
Valkey or Redis OSS (cluster mode enabled) replication group naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**ReplicationGroupDescription**
Your description of the replication group.
**NumCacheClusters**
The total number of nodes you want created with this replication group, primary and read replicas combined.
If you enable Multi-AZ (`AutomaticFailoverEnabled=true`), the value of `NumCacheClusters` must be at least 2.
**CacheNodeType**
The node type for each node in the replication group.
ElastiCache supports the following node types. Generally speaking, the current generation types provide more memory and computational power at lower cost when compared to their equivalent previous generation counterparts.
For more information on performance details for each node type, see [Amazon EC2 Instance Types](https://aws.amazon.com/ec2/instance-types/).
**--data-tiering-enabled**
Set this parameter if you are using an r6gd node type. If you don't want data tiering, set `--no-data-tiering-enabled`. For more information, see [Data tiering in ElastiCache](data-tiering.md).
**CacheParameterGroup**
Specify a parameter group that corresponds to your engine version. If you are running Redis OSS 3.2.4 or later, specify the `default.redis3.2` parameter group or a parameter group derived from `default.redis3.2` to create a Valkey or Redis OSS (cluster mode disabled) replication group. For more information, see [Valkey and Redis OSS parameters](ParameterGroups.Engine.md#ParameterGroups.Redis).
**--network-type**
Either `ipv4`, `ipv` or `dual-stack`. If you choose dual-stack, you must set the `--IpDiscovery` parameter to either `ipv4` or `ipv6`.
**Engine**
redis
**EngineVersion**
6.0
The names of the nodes will be derived from the replication group name by postpending `-00`*\$1* to the replication group name. For example, using the replication group name `myReplGroup`, the name for the primary will be `myReplGroup-001` and the read replicas `myReplGroup-002` through `myReplGroup-006`.
If you want to enable in-transit or at-rest encryption on this replication group, add either or both of the `TransitEncryptionEnabled=true` or `AtRestEncryptionEnabled=true` parameters and meet the following conditions.
+ Your replication group must be running Redis OSS version 3.2.6 or 4.0.10.
+ The replication group must be created in an Amazon VPC.
+ You must also include the parameter `CacheSubnetGroup`.
+ You must also include the parameter `AuthToken` with the customer specified string value for your AUTH token (password) needed to perform operations on this replication group.
The following operation creates the Valkey or Redis OSS (cluster mode disabled) replication group `myReplGroup` with three nodes, a primary and two replicas.
```
https://elasticache.us-west-2.amazonaws.com/
?Action=CreateReplicationGroup
&CacheNodeType=cache.m4.large
&CacheParameterGroup=default.redis6.x
&Engine=redis
&EngineVersion=6.0
&NumCacheClusters=3
&ReplicationGroupDescription=test%20group
&ReplicationGroupId=myReplGroup
&Version=2015-02-02
&SignatureVersion=4
&SignatureMethod=HmacSHA256
&Timestamp=20150202T192317Z
&X-Amz-Credential=
```
For additional information and parameters you might want to use, see the ElastiCache API topic [CreateReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateReplicationGroup.html).
# Creating a replication group in Valkey or Redis OSS (Cluster Mode Enabled) from scratch
You can create a Valkey or Redis OSS (cluster mode enabled) cluster (API/CLI: *replication group*) using the ElastiCache console, the AWS CLI, or the ElastiCache API. A Valkey or Redis OSS (cluster mode enabled) replication group has from 1 to 500 shards (API/CLI: node groups), a primary node in each shard, and up to 5 read replicas in each shard. You can create a cluster with higher number of shards and lower number of replicas totaling up to 90 nodes per cluster. This cluster configuration can range from 90 shards and 0 replicas to 15 shards and 5 replicas, which is the maximum number of replicas allowed.
The node or shard limit can be increased to a maximum of 500 per cluster if the Valkey or Redis OSS 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 [Creating a subnet group](SubnetGroups.Creating.md).
For versions below 5.0.6, the limit is 250 per cluster.
To request a limit increase, see [AWS Service Limits](https://docs.aws.amazon.com/general/latest/gr/aws_service_limits.html) and choose the limit type **Nodes per cluster per instance type**.
**Topics**
+ [Using the ElastiCache Console](#Replication.CreatingReplGroup.NoExistingCluster.Cluster.CON)
+ [Creating a Valkey or Redis OSS (Cluster Mode Enabled) replication group from scratch (AWS CLI)](#Replication.CreatingReplGroup.NoExistingCluster.Cluster.CLI)
+ [Creating a replication group in Valkey or Redis OSS (Cluster Mode Enabled) from scratch (ElastiCache API)](#Replication.CreatingReplGroup.NoExistingCluster.Cluster.API)
## Creating a Valkey or Redis OSS (Cluster Mode Enabled) cluster (Console)
To create a Valkey or Redis OSS (cluster mode enabled) cluster, see [Creating a Valkey or Redis OSS (cluster mode enabled) cluster (Console)](Clusters.Create.md#Clusters.Create.CON.RedisCluster). Be sure to enable cluster mode, **Cluster Mode enabled (Scale Out)**, and specify at least two shards and one replica node in each.
## Creating a Valkey or Redis OSS (Cluster Mode Enabled) replication group from scratch (AWS CLI)
The following procedure creates a Valkey or Redis OSS (cluster mode enabled) replication group using the AWS CLI.
When you create a Valkey or Redis OSS (cluster mode enabled) replication group from scratch, you create the replication group and all its nodes with a single call to the AWS CLI `create-replication-group` command. Include the following parameters.
**--replication-group-id**
The name of the replication group you are creating.
Valkey or Redis OSS (cluster mode enabled) replication group naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**--replication-group-description**
Description of the replication group.
**--cache-node-type**
The node type for each node in the replication group.
ElastiCache supports the following node types. Generally speaking, the current generation types provide more memory and computational power at lower cost when compared to their equivalent previous generation counterparts.
For more information on performance details for each node type, see [Amazon EC2 Instance Types](https://aws.amazon.com/ec2/instance-types/).
**--data-tiering-enabled**
Set this parameter if you are using an r6gd node type. If you don't want data tiering, set `--no-data-tiering-enabled`. For more information, see [Data tiering in ElastiCache](data-tiering.md).
**--cache-parameter-group**
Specify the `default.redis6.x.cluster.on` parameter group or a parameter group derived from `default.redis6.x.cluster.on` to create a Valkey or Redis OSS (cluster mode enabled) replication group. For more information, see [Redis OSS 6.x parameter changes](ParameterGroups.Engine.md#ParameterGroups.Redis.6-x).
**--engine**
redis
**--engine-version**
3.2.4
**--num-node-groups**
The number of node groups in this replication group. Valid values are 1 to 500.
The node/shard limit can be increased to a maximum of 500 per cluster. To request a limit increase, see [AWS Service Limits](https://docs.aws.amazon.com/general/latest/gr/aws_service_limits.html) and select limit type "Nodes per cluster per instance type”.
**--replicas-per-node-group**
The number of replica nodes in each node group. Valid values are 0 to 5.
**--network-type**
Either `ipv4`, `ipv` or `dual-stack`. If you choose dual-stack, you must set the `--IpDiscovery` parameter to either `ipv4` or `ipv6`.
If you want to enable in-transit or at-rest encryption on this replication group, add either or both of the `--transit-encryption-enabled` or `--at-rest-encryption-enabled` parameters and meet the following conditions.
+ Your replication group must be running Redis OSS version 3.2.6 or 4.0.10.
+ The replication group must be created in an Amazon VPC.
+ You must also include the parameter `--cache-subnet-group`.
+ You must also include the parameter `--auth-token` with the customer specified string value for your AUTH token (password) needed to perform operations on this replication group.
The following operation creates the Valkey or Redis OSS (cluster mode enabled) replication group `sample-repl-group` with three node groups/shards (--num-node-groups), each with three nodes, a primary and two read replicas (--replicas-per-node-group).
For Linux, macOS, or Unix:
```
aws elasticache create-replication-group \
--replication-group-id sample-repl-group \
--replication-group-description "Demo cluster with replicas" \
--num-node-groups 3 \
--replicas-per-node-group 2 \
--cache-node-type cache.m4.large \
--engine redis \
--security-group-ids SECURITY_GROUP_ID \
--cache-subnet-group-name SUBNET_GROUP_NAME>
```
For Windows:
```
aws elasticache create-replication-group ^
--replication-group-id sample-repl-group ^
--replication-group-description "Demo cluster with replicas" ^
--num-node-groups 3 ^
--replicas-per-node-group 2 ^
--cache-node-type cache.m4.large ^
--engine redis ^
--security-group-ids SECURITY_GROUP_ID ^
--cache-subnet-group-name SUBNET_GROUP_NAME>
```
The preceding command generates the following output.
```
{
"ReplicationGroup": {
"Status": "creating",
"Description": "Demo cluster with replicas",
"ReplicationGroupId": "sample-repl-group",
"SnapshotRetentionLimit": 0,
"AutomaticFailover": "enabled",
"SnapshotWindow": "05:30-06:30",
"MemberClusters": [
"sample-repl-group-0001-001",
"sample-repl-group-0001-002",
"sample-repl-group-0001-003",
"sample-repl-group-0002-001",
"sample-repl-group-0002-002",
"sample-repl-group-0002-003",
"sample-repl-group-0003-001",
"sample-repl-group-0003-002",
"sample-repl-group-0003-003"
],
"PendingModifiedValues": {}
}
}
```
When you create a Valkey or Redis OSS (cluster mode enabled) replication group from scratch, you are able to configure each shard in the cluster using the `--node-group-configuration` parameter as shown in the following example which configures two node groups (Console: shards). The first shard has two nodes, a primary and one read replica. The second shard has three nodes, a primary and two read replicas.
**--node-group-configuration**
The configuration for each node group. The `--node-group-configuration` parameter consists of the following fields.
+ `PrimaryAvailabilityZone` – The Availability Zone where the primary node of this node group is located. If this parameter is omitted, ElastiCache chooses the Availability Zone for the primary node.
**Example:** us-west-2a.
+ `ReplicaAvailabilityZones` – A comma separated list of Availability Zones where the read replicas are located. The number of Availability Zones in this list must match the value of `ReplicaCount`. If this parameter is omitted, ElastiCache chooses the Availability Zones for the replica nodes.
**Example:** "us-west-2a,us-west-2b,us-west-2c"
+ `ReplicaCount` – The number of replica nodes in this node group.
+ `Slots` – A string that specifies the keyspace for the node group. The string is in the format `startKey-endKey`. If this parameter is omitted, ElastiCache allocates keys equally among the node groups.
**Example:** "0-4999"
The following operation creates the Valkey or Redis OSS (cluster mode enabled) replication group `new-group` with two node groups/shards (`--num-node-groups`). Unlike the preceding example, each node group is configured differently from the other node group (`--node-group-configuration`).
For Linux, macOS, or Unix:
```
aws elasticache create-replication-group \
--replication-group-id new-group \
--replication-group-description "Sharded replication group" \
--engine redis \
--snapshot-retention-limit 8 \
--cache-node-type cache.m4.medium \
--num-node-groups 2 \
--node-group-configuration \
"ReplicaCount=1,Slots=0-8999,PrimaryAvailabilityZone='us-east-1c',ReplicaAvailabilityZones='us-east-1b'" \
"ReplicaCount=2,Slots=9000-16383,PrimaryAvailabilityZone='us-east-1a',ReplicaAvailabilityZones='us-east-1a','us-east-1c'"
```
For Windows:
```
aws elasticache create-replication-group ^
--replication-group-id new-group ^
--replication-group-description "Sharded replication group" ^
--engine redis ^
--snapshot-retention-limit 8 ^
--cache-node-type cache.m4.medium ^
--num-node-groups 2 ^
--node-group-configuration \
"ReplicaCount=1,Slots=0-8999,PrimaryAvailabilityZone='us-east-1c',ReplicaAvailabilityZones='us-east-1b'" \
"ReplicaCount=2,Slots=9000-16383,PrimaryAvailabilityZone='us-east-1a',ReplicaAvailabilityZones='us-east-1a','us-east-1c'"
```
The preceding operation generates the following output.
```
{
"ReplicationGroup": {
"Status": "creating",
"Description": "Sharded replication group",
"ReplicationGroupId": "rc-rg",
"SnapshotRetentionLimit": 8,
"AutomaticFailover": "enabled",
"SnapshotWindow": "10:00-11:00",
"MemberClusters": [
"rc-rg-0001-001",
"rc-rg-0001-002",
"rc-rg-0002-001",
"rc-rg-0002-002",
"rc-rg-0002-003"
],
"PendingModifiedValues": {}
}
}
```
For additional information and parameters you might want to use, see the AWS CLI topic [create-replication-group](https://docs.aws.amazon.com/cli/latest/reference/elasticache/create-replication-group.html).
## Creating a replication group in Valkey or Redis OSS (Cluster Mode Enabled) from scratch (ElastiCache API)
The following procedure creates a Valkey or Redis OSS (cluster mode enabled) replication group using the ElastiCache API.
When you create a Valkey or Redis OSS (cluster mode enabled) replication group from scratch, you create the replication group and all its nodes with a single call to the ElastiCache API `CreateReplicationGroup` operation. Include the following parameters.
**ReplicationGroupId**
The name of the replication group you are creating.
Valkey or Redis OSS (cluster mode enabled) replication group naming constraints are as follows:
+ Must contain 1–40 alphanumeric characters or hyphens.
+ Must begin with a letter.
+ Can't contain two consecutive hyphens.
+ Can't end with a hyphen.
**ReplicationGroupDescription**
Description of the replication group.
**NumNodeGroups**
The number of node groups you want created with this replication group. Valid values are 1 to 500.
**ReplicasPerNodeGroup**
The number of replica nodes in each node group. Valid values are 1 to 5.
**NodeGroupConfiguration**
The configuration for each node group. The `NodeGroupConfiguration` parameter consists of the following fields.
+ `PrimaryAvailabilityZone` – The Availability Zone where the primary node of this node group is located. If this parameter is omitted, ElastiCache chooses the Availability Zone for the primary node.
**Example:** us-west-2a.
+ `ReplicaAvailabilityZones` – A list of Availability Zones where the read replicas are located. The number of Availability Zones in this list must match the value of `ReplicaCount`. If this parameter is omitted, ElastiCache chooses the Availability Zones for the replica nodes.
+ `ReplicaCount` – The number of replica nodes in this node group.
+ `Slots` – A string that specifies the keyspace for the node group. The string is in the format `startKey-endKey`. If this parameter is omitted, ElastiCache allocates keys equally among the node groups.
**Example:** "0-4999"
**CacheNodeType**
The node type for each node in the replication group.
ElastiCache supports the following node types. Generally speaking, the current generation types provide more memory and computational power at lower cost when compared to their equivalent previous generation counterparts.
For more information on performance details for each node type, see [Amazon EC2 Instance Types](https://aws.amazon.com/ec2/instance-types/).
**--data-tiering-enabled**
Set this parameter if you are using an r6gd node type. If you don't want data tiering, set `--no-data-tiering-enabled`. For more information, see [Data tiering in ElastiCache](data-tiering.md).
**CacheParameterGroup**
Specify the `default.redis6.x.cluster.on` parameter group or a parameter group derived from `default.redis6.x.cluster.on` to create a Valkey or Redis OSS (cluster mode enabled) replication group. For more information, see [Redis OSS 6.x parameter changes](ParameterGroups.Engine.md#ParameterGroups.Redis.6-x).
**--network-type**
Either `ipv4`, `ipv` or `dual-stack`. If you choose dual-stack, you must set the `--IpDiscovery` parameter to either `ipv4` or `ipv6`.
**Engine**
redis
**EngineVersion**
6.0
If you want to enable in-transit or at-rest encryption on this replication group, add either or both of the `TransitEncryptionEnabled=true` or `AtRestEncryptionEnabled=true` parameters and meet the following conditions.
+ Your replication group must be running Redis OSS version 3.2.6 or 4.0.10.
+ The replication group must be created in an Amazon VPC.
+ You must also include the parameter `CacheSubnetGroup`.
+ You must also include the parameter `AuthToken` with the customer specified string value for your AUTH token (password) needed to perform operations on this replication group.
Line breaks are added for ease of reading.
```
https://elasticache.us-west-2.amazonaws.com/
?Action=CreateReplicationGroup
&CacheNodeType=cache.m4.large
&CacheParemeterGroup=default.redis6.xcluster.on
&Engine=redis
&EngineVersion=6.0
&NumNodeGroups=3
&ReplicasPerNodeGroup=2
&ReplicationGroupDescription=test%20group
&ReplicationGroupId=myReplGroup
&Version=2015-02-02
&SignatureVersion=4
&SignatureMethod=HmacSHA256
&Timestamp=20150202T192317Z
&X-Amz-Credential=
```
For additional information and parameters you might want to use, see the ElastiCache API topic [CreateReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateReplicationGroup.html).