How to change to T2 unlimited for an AWS EC2 instance type

Published on August 21, 2018
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Amazon’s T2 has a really good value proposition, however, with CPUs getting throttled once credits were exhausted, people refrained from using them for production workloads. This changed with the introduction of T2 unlimited where you pay a bit more when credits are exhausted but do not encounter CPU throttling issues once the burst credits are exhausted. Understanding how T2 unlimited works may be helpful prior to implementing the below steps to turn on T2 unlimited for an EC2 instance type.

For production systems where there can be unexpected spikes, it is suggested to have a T2 unlimited option enabled so as to avert potential CPU throttling issues.

With T2 unlimited you can sustain high CPU performance over any desired time frame while still keeping your costs as low as possible. This feature can be enabled when:

  • the instance is created and launched;
  • the instance is already started;

Turning on T2 unlimited is a real-time change – no power up and down is needed to realize these settings change. The fact that you can enable unlimited while the instance is running is a great thing as in normal conditions in order to resize an instance you have to stop it, then change the instance type, and finally re-start it again.

Turning on T2 unlimited is a real-time change – no power up and down is needed to realize these settings change.

Shutting down a T2 instance may not be a great idea as you encounter a reset of credits you may have accumulated while your T2 was running below thresholds. Additionally, turning T2 unlimited option once you are encountering CPU throttling issues may be too late!

Enabling T2 unlimited option is easy and once enabled T2 unlimited allows you to run over the baseline of the T2 that you have, e.g if you have a t2.small instance at an average of 25% CPU utilization (5% over the baseline) for 24 hours you will be charged an additional 6 cents (5 cents per vCPU-hour * 1 vCPU * 5% * 24 hours).

To launch a T2 Unlimited instance from the EC2 Console, select any T2 instance and then click on Enable next to T2 Unlimited:configure t2 instance

And here’s how to switch a running instance from T2 Standard to T2 Unlimited:

turn on t2 unlimited

Then on the next screen click Enable:t2 accept change

For an instance of T2 if you wish to not encounter a throttled CPU experience we suggest enabling T2 unlimited dynamically with our opensource contributed code at: https://github.com/cloudsqueeze/aws-lambda which will allow you to enable/disable T2 unlimited prior to CPU credits getting exhausted. The steps to install this are as follows:

  1. Go to AWS Serverless repo where we host the T2 app: Enable T2 unlimited option for a T class in real-time to create the IAM policy as explained in the Readme and click Deploy;opensource aws
  2. In next screen pick the Region and the instance id that you want to have the lambda enabled then click on Deploy;customize serverless lambda
  3. If all is deployed correctly you should get the Application successfully deployed screen;deploy the lambda
  4. At this point the application is deployed and active on the InstanceId and region you picked;
  5. To delete the application go to CloudFormation screen, pick the T2 lambda and then click on Actions and Delete.deploy the lambda

As a rule of thumb if you notice that the CPU usage on your T2 instance is bigger than the baseline then it is recommended to enable T2 unlimited otherwise performance will degrade. Eventually, use https://github.com/cloudsqueeze/aws-lambda which will allow you to enable/disable T2 unlimited when CPU credits are close to ending.

The following table shows the baseline values for all T2 instances:t2 threshold credits

If you encounter issues in the process of removing an elastic IP from a stopped EC2 instance or have a question about any of our AWS Tutorials, please reach out to us with a comment and will add this to the FAQs. If you would like to partner with us and develop AWS open source scripts for these steps, reach out to us.

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