We often talk about the very low AWS costs. We are usually referring to the AWS instances that run the load tests. There is another AWS cost that you should be aware of and that is the AWS data costs. It’s usually very low also as you can see here in this AWS post. But depending on your test, you may need to keep an eye on it. So this post will talk about AWS data costs for load testing.
The idea for this post came about when a customer contacted us and asked why their AWS cost was higher than they expected. The customer provided us with their information:
- 10 On-Demand m5.12xlarge Instances, each server cost $2.4480.
- test duration of just 10 minutes
- but the cost is much more – see the image below
We explained it to them and thought that others might find this information helpful. As we said above, AWS charges for data and servers. RedLine13 displays the server cost that we pull from AWS documented costs. We intentionally assume the worst case with the server running for the full hour after the test completes since you have the option to leave servers running for 1 hour. Most people set the time amount to much less and will therefore save money. The other AWS cost is the data or network bandwidth. In this case above, you can see that the test used a lot of bandwidth, over 66GB. This drove their AWS costs higher than they expected. Just to be clear, this is strictly an AWS cost that you pay directly to AWS. RedLine13 does not get any money at all.
You can read another blog post about keeping your AWS costs low. This is a 50,000 user example that cost around $2. One additional way to keep costs down is to use spot pricing, which you can get at a significant discount. Combine that with per minute pricing in AWS, short tests can be extremely cheap.
If you want to know how much your AWS costs will be before you run a large test, how can you figure it out? As you might expect, it depends on many things which we’ve discussed. The best way is to run a small test and extrapolate from there.
If you’d like to learn more about AWS costs, check out this post AWS Costs and Continuous Load Testing Costs.