AWS vCPU Limit Prerequisites for SaaS Product

Overview

When you launch your SaaS product, it provisions EC2 instances in your AWS account via Terraform. The instance types depend on the ratio you select.

By default, AWS imposes vCPU limits on EC2 instance families, which may prevent your instances from launching. You must request vCPU quota increases from AWS before launching the product.

Required EC2 Instances by Ratio

Ratio	EC2 Instances (Types)	vCPUs per Instance	Total vCPUs Needed	EC2 Instance Family Quota to Increase
2/1	1 × c5n.4xlarge 3 × c6i.2xlarge	16 8	40	c5n quota (16 vCPUs) c6i quota (24 vCPUs)
4/1	1 × c5n.9xlarge 5 × c6i.2xlarge	36 8	76	c5n quota (36 vCPUs) c6i quota (40 vCPUs)
8/1	1 × c5n.18xlarge 9 × c6i.2xlarge	72 8	144	c5n quota (72 vCPUs) c6i quota (72 vCPUs)

Step 1 — Check Current vCPU Limits

1. Sign in to the AWS Management Console.

2. Go to Service Quotas.

3. Search for "Running On-Demand Standard (A, C, D, H, I, M, R, T, Z) instances".

4. Look for the quota specific to the instance family:

   • c5n

   • c6i

   • Direct link to EC2 quotas

5. Compare your current limit to the total vCPUs needed from the table above.

Step 2 — Request vCPU Limit Increase

1. In Service Quotas, click the instance family quota (e.g., Running On-Demand C instance vCPUs).

2. Click Request quota increase.

3. Enter the new limit — set it higher than the total vCPUs you need (we recommend at least +20% buffer).

4. Submit the request.

5. AWS typically approves within a few hours to 1 business day.

Step 3 — Verify Before Launch

Once AWS approves your request:

1. Go back to Service Quotas.

2. Confirm the new vCPU limit for each required family.

3. Proceed to launch the SaaS product.

Example for 4/1 Ratio

If you choose a 4/1 ratio, you need:

• c5n quota → at least 36 vCPUs

• c6i quota → at least 40 vCPUs

We recommend requesting:

• c5n quota → 50 vCPUs

• c6i quota → 50 vCPUs