Azure Service Fabric cost calculation, nodes vs instances

Question

I've been trying to establish the cost of running as standard 5-instance Service Fabric cluster.

I am using Azure Pricing Calculator and it talks about Scale Sets.

What is a 'scale set'? Does one scale set include 5 instances or do I need 5 scale sets for a 5 instance cluster?

(By default the calculator adds three scale sets.)

Answer 1

A VM scale set is a resource that enables deployment and scaling of identical VMs. Service Fabric clusters are built on top of scale sets to enable elastic scale in and out of your cluster based on load. There is no cost associated with the scale set resource itself, only the underlying VMs.

At a minimum, a production Service Fabric cluster requires one scaleset with at least 5 nodes (for dev/test environments, you can drop to 3).

So why do you see multiple scale sets in the pricing calculator?

Service Fabric supports the notion of node types, which allow you to segment nodes within your cluster. A common usage is to differentiate between front-end and back-end machines with different hardware SKUs and network configurations. You can then use placement constraints to limit certain types of services to certain types of nodes. Each node type maps to one VM scale set, enabling you to scale each node type independently.

How many node types/scale sets you need is really up to you based on how much segmentation you want in your cluster.