Boot disk images in GCP - Step-by-Step Execution

Process Flow - Boot disk images

Select Boot Disk Image

↓

Create VM Instance

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Attach Boot Disk with Image

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Start VM

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VM boots using Disk Image

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VM Ready for Use

This flow shows how a virtual machine (VM) boots using a selected boot disk image in Google Cloud Platform.

Execution Sample

GCP

gcloud compute instances create my-vm \
  --image-family=debian-11 \
  --image-project=debian-cloud \
  --boot-disk-size=10GB

This command creates a VM named 'my-vm' using the Debian 11 boot disk image with a 10GB boot disk.

Process Table

Step	Action	Input/Parameter	Result/State
1	Select boot disk image	image-family=debian-11, image-project=debian-cloud	Image Debian 11 selected
2	Create VM instance	name=my-vm	VM instance 'my-vm' created
3	Attach boot disk	boot-disk-size=10GB	Boot disk of 10GB attached with Debian 11 image
4	Start VM	none	VM 'my-vm' starts booting
5	VM boots	boot disk image	VM boots successfully using Debian 11 image
6	VM ready	none	VM 'my-vm' is ready for use

💡 VM boots successfully using the selected boot disk image and is ready for use

Status Tracker

Variable	Start	After Step 1	After Step 3	After Step 5	Final
boot_disk_image	none	debian-11 from debian-cloud	attached to VM	used to boot VM	in use by running VM
vm_instance	none	none	created as 'my-vm'	booting	running and ready

Key Moments - 3 Insights

Why do we specify both image-family and image-project when selecting a boot disk image?

Because image-family selects the latest image in that family, and image-project tells GCP where to find that image. This is shown in execution_table row 1.

What happens if the boot disk size is too small?

The VM creation will fail or the VM may not boot properly because the disk cannot hold the OS image. This relates to execution_table row 3 where the boot disk is attached.

Does the VM start automatically after creation?

Yes, by default the VM starts after creation as shown in execution_table row 4 and 5.

Visual Quiz - 3 Questions

Look at the execution table, what is the boot disk image selected at step 1?

A ubuntu-20-04 from ubuntu-cloud

B windows-server-2019 from windows-cloud

C debian-11 from debian-cloud

D centos-7 from centos-cloud

💡 Hint

Check the 'Action' and 'Result/State' columns in row 1 of the execution_table.

At which step does the VM instance get created?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look at the 'Action' column for VM creation in the execution_table.

If the boot disk size was changed to 5GB, which step would be directly affected?

A Step 1

B Step 3

C Step 2

D Step 5

💡 Hint

Refer to the 'Attach boot disk' action in the execution_table.

Concept Snapshot

Boot disk images in GCP are used to start VMs.
You select an image family and project to pick the OS.
Create a VM and attach a boot disk with that image.
The VM boots from this disk and becomes ready.
Boot disk size must be enough for the OS.
Use gcloud commands with --image-family and --image-project.

Full Transcript

Boot disk images are pre-made operating system disks used to start virtual machines in Google Cloud Platform. The process begins by selecting an image family and project, which tells GCP which OS version to use. Then, a VM instance is created with a boot disk attached that contains this image. When the VM starts, it boots from this disk image and becomes ready for use. The boot disk size must be sufficient to hold the OS. The example command shows creating a VM named 'my-vm' using the Debian 11 image with a 10GB boot disk. The execution table traces each step from image selection to VM readiness, and the variable tracker shows how the boot disk image and VM instance states change over time.