About components in AWS ElastiCache Redis OSS

In Amazon ElastiCache for Redis OSS Serverless, the Data Store refers to the in-memory data storage component, similar to traditional Redis. It's where your data is stored and accessed quickly for high-performance operations.

When requests are sent to the Redis cluster, ECPUs (ElastiCache Processing Units) are generated to handle the workload. ECPUs are a measure of the compute capacity used to process requests. The workflow for generating ECPUs is dynamic and scales based on the incoming requests. ElastiCache automatically calculates and allocates the necessary ECPUs to fit the request load, ensuring optimal performance without manual intervention.

Setting minimum Data Store capacity and ECPU consumption serves several purposes:

1. Ensuring baseline performance: By setting minimums, you guarantee a certain level of resources are always available, even during periods of low activity.

2. Faster scaling: When traffic increases, having a minimum capacity allows for quicker scaling as some resources are already allocated.

3. Predictable costs: Minimum settings help in establishing a baseline for your expenses.

4. Improved responsiveness: With minimum resources always available, your application can respond more quickly to sudden spikes in traffic.

The benefit of setting these minimums is that it provides a balance between cost-efficiency and performance. It ensures your application has the necessary resources to handle sudden increases in load while avoiding over-provisioning during periods of low activity. This approach helps in maintaining consistent performance and can be particularly useful for applications with variable workloads or those that require quick response times.

Sources
ElastiCache components and features - Amazon ElastiCache
Valkey-, Memcached-, and Redis OSS-Compatible Cache – Amazon ElastiCache with Valkey- and Redis OSS-compatibility - AWS
Determining your ElastiCache cluster requirements - Amazon ElastiCache

Hi,

To your final question, setting minimum Data Store or total ECPU requests is here to allow you to have minimum guaranteed performance. If your request rate to the cache suddenly peaks, it will take some time for the cache to scale up ECPU to respond efficiently to this higher throughput.

So, you should raise the capacity reservation if you want to avoid this scaling latency. But it has a cost as you noticed: so, you have to study your cache traffic pattern and define your budget allowance to define optimal capacity reservation.

Best,

Didier