Let’s assume that you started off with the lower editions and capacity with Redis and your developers tell you to scale the Redis cluster. Well first to use a cluster you need premium. Below under the cluster size option in the Azure portal you will see the message:
This is because I am using standard, so lets upgrade to premium. You can find this under the scale option.
I select P1. There is an important message here, worth paying attention to.
This sort of scaling is called scaling up.
How that I am on Premium I have access to shards, I know what to show you how to scale OUT by increasing the shard count thus functions are distributed across multiple Redis processes. Basically, when the new shards are provisioned and added to the Redis server cluster, data is then resharded across all shards.
What you need to do is click on enable clustering and enter number greater than 1 for the shard count.
Typically, you won’t lose data when scaling upwards, the only chance of data loss is if the data size exceeds the new smaller size when you scale down. (If you have basic and move to something else, data is lost)