Amazon ElastiCache
API Reference (API Version 2015-02-02)

ModifyReplicationGroupShardConfiguration

Modifies a replication group's shards (node groups) by allowing you to add shards, remove shards, or rebalance the keyspaces among exisiting shards.

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

ApplyImmediately

Indicates that the shard reconfiguration process begins immediately. At present, the only permitted value for this parameter is true.

Value: true

Type: Boolean

Required: Yes

NodeGroupCount

The number of node groups (shards) that results from the modification of the shard configuration.

Type: Integer

Required: Yes

ReplicationGroupId

The name of the Redis (cluster mode enabled) cluster (replication group) on which the shards are to be configured.

Type: String

Required: Yes

NodeGroupsToRemove.NodeGroupToRemove.N

If the value of NodeGroupCount is less than the current number of node groups (shards), then either NodeGroupsToRemove or NodeGroupsToRetain is required. NodeGroupsToRemove is a list of NodeGroupIds to remove from the cluster.

ElastiCache for Redis will attempt to remove all node groups listed by NodeGroupsToRemove from the cluster.

Type: Array of strings

Length Constraints: Minimum length of 1. Maximum length of 4.

Pattern: \d+

Required: No

NodeGroupsToRetain.NodeGroupToRetain.N

If the value of NodeGroupCount is less than the current number of node groups (shards), then either NodeGroupsToRemove or NodeGroupsToRetain is required. NodeGroupsToRetain is a list of NodeGroupIds to retain in the cluster.

ElastiCache for Redis will attempt to remove all node groups except those listed by NodeGroupsToRetain from the cluster.

Type: Array of strings

Length Constraints: Minimum length of 1. Maximum length of 4.

Pattern: \d+

Required: No

ReshardingConfiguration.ReshardingConfiguration.N

Specifies the preferred availability zones for each node group in the cluster. If the value of NodeGroupCount is greater than the current number of node groups (shards), you can use this parameter to specify the preferred availability zones of the cluster's shards. If you omit this parameter ElastiCache selects availability zones for you.

You can specify this parameter only if the value of NodeGroupCount is greater than the current number of node groups (shards).

Type: Array of ReshardingConfiguration objects

Required: No

Response Elements

The following element is returned by the service.

ReplicationGroup

Contains all of the attributes of a specific Redis replication group.

Type: ReplicationGroup object

Errors

For information about the errors that are common to all actions, see Common Errors.

InsufficientCacheClusterCapacity

The requested cache node type is not available in the specified Availability Zone. For more information, see InsufficientCacheClusterCapacity in the ElastiCache User Guide.

HTTP Status Code: 400

InvalidCacheClusterState

The requested cluster is not in the available state.

HTTP Status Code: 400

InvalidParameterCombination

Two or more incompatible parameters were specified.

HTTP Status Code: 400

InvalidParameterValue

The value for a parameter is invalid.

HTTP Status Code: 400

InvalidReplicationGroupState

The requested replication group is not in the available state.

HTTP Status Code: 400

InvalidVPCNetworkStateFault

The VPC network is in an invalid state.

HTTP Status Code: 400

NodeGroupsPerReplicationGroupQuotaExceeded

The request cannot be processed because it would exceed the maximum allowed number of node groups (shards) in a single replication group. The default maximum is 15

HTTP Status Code: 400

NodeQuotaForCustomerExceeded

The request cannot be processed because it would exceed the allowed number of cache nodes per customer.

HTTP Status Code: 400

ReplicationGroupNotFoundFault

The specified replication group does not exist.

HTTP Status Code: 404

ServiceLinkedRoleNotFoundFault

The specified service linked role (SLR) was not found.

HTTP Status Code: 400

Examples

Add shards

The following example adds shards to the replication group my-cluster so that at the completion of the call there are 4 shards. The availability zones for the nodes in the shards are specified by the parameter ReshardingConfiguration.ReshardingConfiguration.N.PreferredAvailabilityZones.AvailabilityZone.N. If there are already 4 shards in this replication group, the call fails.

https://elasticache.us-east-2.amazonaws.com/ ?Action=ModifyReplicationGroupShardConfiguration &ApplyImmediately=true &NodeGroupCount=4 &ReplicationGroupId=my-cluster &ReshardingConfiguration.ReshardingConfiguration.1.PreferredAvailabilityZones.AvailabilityZone.1=us-east-2a &ReshardingConfiguration.ReshardingConfiguration.1.PreferredAvailabilityZones.AvailabilityZone.2=us-east-2c &ReshardingConfiguration.ReshardingConfiguration.2.PreferredAvailabilityZones.AvailabilityZone.1=us-east-2b &ReshardingConfiguration.ReshardingConfiguration.2.PreferredAvailabilityZones.AvailabilityZone.2=us-east-2a &ReshardingConfiguration.ReshardingConfiguration.3.PreferredAvailabilityZones.AvailabilityZone.1=us-east-2c &ReshardingConfiguration.ReshardingConfiguration.3.PreferredAvailabilityZones.AvailabilityZone.2=us-east-2d &ReshardingConfiguration.ReshardingConfiguration.4.PreferredAvailabilityZones.AvailabilityZone.1=us-east-2d &ReshardingConfiguration.ReshardingConfiguration.4.PreferredAvailabilityZones.AvailabilityZone.2=us-east-2c &Version=2015-02-02 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20171002T192317Z &X-Amz-Credential=<credential>

Remove shards

The following example removes two shards from the replication group my-cluster. leaving 2 shards. When removing shards, the parameter NodeGroupsToRemove.NodeGroupToRemove is required.

You cannot remove the last shard leaving zero shards.

https://elasticache.us-east-2.amazonaws.com/ ?Action=ModifyReplicationGroupShardConfiguration &ApplyImmediately=true &NodeGroupCount=2 &ReplicationGroupId=my-cluster &NodeGroupsToRemove.NodeGroupToRemove.1=0002 &NodeGroupsToRemove.NodeGroupToRemove.2=0003 &Version=2015-02-02 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20171002T192317Z &X-Amz-Credential=<credential>

Rebalance shards

The following rebalances the keyspaces among the existing shards in the replication group my-cluster. The value specified by NodeGroupCount must be the existing number of shards. If the keyspaces are already balanced the call fails.

https://elasticache.us-east-2.amazonaws.com/ ?Action=ModifyReplicationGroupShardConfiguration &ApplyImmediately=true &NodeGroupCount=4 &ReplicationGroupId=my-cluster &Version=2015-02-02 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20171002T192317Z &X-Amz-Credential=<credential>

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: