There are times when you want to bring up a copy of the instance running on EC2. A common use case can be your in use instance faces some ad-hoc problem and stops responding. You want to bring up the exact replica as soon as possible to minimize the impact on end-users. Fortunately, this can be done easily in a couple of steps.
The first step is to create an image or AMI (Amazon Machine Image). As the name suggests, AMI gives you an image of the current state of the machine. All you need to do to create an AMI is right-click on an EC2 instance, and select option to create the image.
Once the image is created, you will be able to see it under the AMIs section. Creating an instance from Image is equally easy. All you need to do is select the AMI and click launch.
You will need to choose Instance type, security group, key pair, etc just like when creating a new instance. When the instance is launched, you will see it is exact replica of the original image. This can be handy in a situation where your server just went down and you need to bring the application up. You can bring a new replica instance up and assign the Elastic IP, your application is back in minutes.