Understanding the EC2 Instance Lifecycle: A Simple Guide

Amazon EC2 instances are virtual servers in the cloud, and they go through various stages from creation to termination. Let’s break down these stages in an easy-to-understand way.

1. Launching Your Instance

Pending State: When you first create an EC2 instance, it enters the pending state. Think of this as the preparation stage. At this point, the instance is getting ready to start, and you aren’t being billed yet. During this phase, AWS sets up everything needed for your instance, like copying the system image to the root device and setting up network components.

2. Running Your Instance

Running State: Once the instance is ready, it moves to the running state. Now, your instance is active, and billing starts. In this state, you can interact with your instance, such as by rebooting, stopping, or even terminating it.

3. Rebooting Your Instance

Rebooting: Rebooting an instance is like restarting your computer. The instance keeps its public DNS name and both its public and private IP addresses. If the instance has an IPv6 address, it also remains the same. All the data on the instance’s local storage (instance store volumes) is preserved.

4. Stopping Your Instance

Stopping State: When you stop an instance, it first moves to the stopping state and then to the stopped state. This is like shutting down your laptop. You can only stop and start an instance if it uses Amazon Elastic Block Store (EBS) for its root device. When stopped, the instance keeps its private IP address and any IPv6 address it has. If you start it again, it might be placed on a different physical server.

Stop-Hibernate: If you choose to stop-hibernate, the instance saves its current state to disk, which makes restarting faster because it picks up right where it left off.

5. Terminating Your Instance

Terminated State: Terminating an instance is like permanently shutting down and disposing of your computer. The instance’s local storage is erased, and you lose its public and private IP addresses. Once an instance is in the shutting down or terminated state, you stop being billed for it.

Difference Between Stop and Stop-Hibernate

• Stop: When you stop an instance, it shuts down and moves to the stopped state. You won’t be charged for the instance’s usage or data transfer, but you will still be charged for any storage associated with it. Any data in the instance’s memory (RAM) is lost.
• Stop-Hibernate: When you use stop-hibernate, the instance saves its memory (RAM) contents to the EBS root volume before shutting down. This makes restarting faster and allows the instance to continue from where it left off. To use this feature, hibernation must be enabled, and the instance must meet certain requirements.

By understanding these states and their implications, you can manage your EC2 instances more effectively and control your costs.