Scaling behaviour on ElastiCache Redis (Cluster Mode Disable)

Question

When I perform a scaling down (e.g. t3.small to t3.micro) on ElastiCache Redis (Cluster mode disable) cluster, will the data be restored from the previous cluster? Is there any difference between single-node cluster and cluster with replicas?

P.S. The doc on scaling up cluster did mentioned the data is copied to the new cluster. However there is not mentioned in scaling down document.

P.S. The doc on scaling up cluster [did mentioned](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Scaling.RedisStandalone.ScaleUp.html) the data is copied to the new cluster. However there is not mentioned in [scaling down document](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Scaling.RedisStandalone.ScaleDown.html).

Answer

Hi, the doc confirms that data is copied across nodes during vertical scaling (up or down): see https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/redis-cluster-vertical-scaling.html

```
The scale up and scale down processes rely on creating clusters with newly selected node types 
and synchronizing the new nodes with the previous ones.

While the vertical scaling process is designed to remain fully online, it does rely on synchronizing 
data between the old node and the new node. We recommend that you initiate scale up/down 
during hours when you expect data traffic to be at its minimum.
```

Best,

Didier

Scaling behaviour on ElastiCache Redis (Cluster Mode Disable)

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