为什么不在 AWS 上获得 2 个纳米实例而不是 1 个微型实例？

Question

I'm choosing instances do run microservices on an AWS EKS cluster.

When reading about it on this article an taking a look on the aws docs it seems that choosing many small instances instead of on larger instance results on a better deal.

There seems to be no downside on taking, for instance, 2 t3.nano (2 vCPU / 0.5GiB each) vs 1 t3.micro (2 vCPU / 1GiB each). The price and the memory are the same but the CPU provided has a huge difference the more instances you get.

I assume there are some processes running on each machine by default, but I found no places metioning its impact on the machine resources or usage. Is it negligible? Is there any advantage on taking one big instance instead?

Answer 1

The issue is whether or not your computing task can be completed on the smaller instances and also there is an overhead involved in instance-to-instance communication that isn't present in intra-instance communication.

So, it is all about fitting your solution onto the instances and your requirements.

Answer 2

There is no right answer to this question. The answer depends on your specific workload, and you have to try out both approaches to find out what works best for your case. There are advantages and disadvantages to both approaches.

For example, if the OS takes 200 MB for each instance, you will be left with only 600 MB both nano instances combined vs the 800 MB on the single micro instance.

When the cluster scales out, initializing 2 nano instances might roughly take twice as much time as initializing one micro instance to provide the same additional capacity to handle the extra load.

Also, as noted by Cargo23, inter-instance communication might increase the latency of your application.