Hi, everyone, welcome to this lecture. In this lecture, we're going to cover VM instance management. We'll touch on what management tasks require you to stop an instance, and what happens when you stop it. So let's jump in.

There will be times when you need to stop and restart a VM instance. When you stop a VM instance, the instance shuts down the guest OS and the instance loses its application state. That said, the instance retains configured persistent disks, internal IPs, and MAC addresses. Basically, what happens when you stop an instance, is that the instance gets reset to its power-on state.

Stopping an instance is necessary when you need to perform many different administrative tasks. For example, if you need to change the machine type, or add and remove attached disks, you'll need to stop the instance. You'll also need to stop the instance if you want to change the minimum CPU platform, add or remove GPUs, or basically resize the instance.

It's important to note that when you stop an instance, the Compute Engine sends an ACPI Power Off signal to the instance itself. This causes the guest operating system to perform a clean shutdown before powering off. Compute Engine will then wait a bit to allow the guest OS to finish shutting down before transitioning the instance to the terminated state.

Although a stopped instance incurs no charges, resources that are attached to the instance will still continue to incur charges. An example of this would be a persistent disk or an external IP address. Both resources would continue to incur charges, even after the instance is stopped, because those resources are still allocated. They don't go away when the instance is stopped unless you reconfigure the stopped instance to not use those resources, and then delete the resources.

In the next lesson, I'll show you how to use the portal to stop and start a VM instance. I'll then show you how to stop and start the instance using gcloud.