AWS ElastiCache - Scaling the Clusters


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As the demand for the ElastiCache service increases we eventually reach a point where we need to increase the memory and processing power allocated to Cache configuration. This is known as scaling up the cluster. But as the cache server is already running, we have certain constraints under which the scale up can happen.

  • All reads from and writes to the cache cluster are stopped.

  • A new cache cluster with the new node type is created in the same Availability Zone as the existing cache cluster.

  • The cache data in the existing cache cluster is copied to the new cache cluster. How long this process takes depends upon your node type and how much data is in the cache cluster.

  • Reads and writes are resumed using the new cache cluster. Because the new cache cluster's endpoints are the same as they were for the old cache cluster, there is no need to update the endpoints in your application.

  • ElastiCache deletes the old cache cluster.

Below are the two steps we follow to achieve the scaling up of a cluster.

Choosing the Cluster

We login to the AWS console and go to the ElastiCache dashboard. From the dashboard in the left we choose the cluster type as Redis. Then we see the name of the cluster as a hyperlink in the ElastiCache dashboard. We click on the check box to the left of the name of the cluster. This shows the option to modify the cluster along with other options.

scalingup_cluster.jpg

Changing the Node Type

Next, we modify the cluster to choose the required node type of higher configuration. After clicking on the modify button we get the option to change the node type as shown in the below diagram. Clicking on the modify button after finalizing the node type configuration brings in the new cache size to the node.

scalingup_cluster_2.jpg

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