If you are doing large scale testing, you may run into limits on your AWS account. They fall into a number of categories as this great post on AWS Limits points out. Here are the three key ones:
Increased EC2 Instances – this is where you can request the ability increase the number of EC2 instances you can run. For example if you want to emulate 50,000 users, you may need 200 servers.
Vulnerability Testing Request Form – If you are doing large scale tests, Amazon will likely notice the increased load and may shut down your servers. This is to help prevent Denial of Service attacks. You will receive a notice if this happens, and hopefully this form will help you avoid being shut down during the middle of your tests.
Spot Instance Limits – In December of 2013 Amazon put in place limits on the number of spot instances you can spin up per region to 5. Since RedLine allows you to run instances from all Regions on the largest servers, you should still have plenty of capacity for large tests. You can also request Amazon for permission to exceed the limits as well as run your own regular instances.
If you do not have an Amazon AWS account, you can sign up for one easily at http://aws.amazon.com/. Signing up is free and you will only pay for the services that are used. As an example, if you do a load test of 50,000 users for an hour the approximate cost is $2.00 and would be charged to your account on Amazon. There is no fee from RedLine.