Boot disk images in GCP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a boot disk image in Google Cloud Platform?

A boot disk image is a pre-configured template that contains an operating system and software. It is used to create the boot disk for a virtual machine instance in Google Cloud.

beginner

How does a boot disk image relate to a VM instance startup?

When a VM instance starts, it uses the boot disk image to load the operating system and initial software needed to run the instance.

intermediate

Can you customize a boot disk image in GCP?

Yes, you can create custom boot disk images by configuring a VM instance and then saving its disk as an image to reuse for other instances.

intermediate

What is the difference between a public image and a custom image in GCP?

Public images are provided by Google and include common OS options. Custom images are created by users from their own VM disks to include specific configurations or software.

beginner

Why is it important to choose the right boot disk image for your VM?

Choosing the right boot disk image ensures your VM has the correct operating system and software environment, which affects performance, compatibility, and security.

What does a boot disk image contain in GCP?

A Network configuration only

B User data and application logs

C Operating system and software to start a VM

D Backup files of VM

A boot disk image contains the operating system and software needed to start a virtual machine.

Which of the following is true about custom boot disk images?

A They are created by users from existing VM disks

B They can only be created by Google

C They cannot be used to create new VMs

D They include only network settings

Custom boot disk images are created by users from existing VM disks to reuse specific configurations.

What happens if you choose the wrong boot disk image for your VM?

A The VM will always start successfully

B The VM will connect to the wrong network

C The VM will delete all data automatically

D The VM might have performance or compatibility issues

Choosing the wrong boot disk image can cause performance or compatibility problems for the VM.

Public boot disk images in GCP are:

A Provided by Google with common operating systems

B Created by users for private use

C Only available for Windows OS

D Automatically deleted after VM shutdown

Public boot disk images are provided by Google and include common operating systems like Linux and Windows.

When does a VM instance use the boot disk image?

A Only during shutdown

B When starting up to load the OS

C When backing up data

D When connecting to the internet

The VM uses the boot disk image during startup to load the operating system.

Explain what a boot disk image is and why it is important for a VM instance in GCP.

Think about what a VM needs to start and run.

Describe the difference between public and custom boot disk images in Google Cloud Platform.

Consider who creates the image and why.

Practice

1. What is the main purpose of a boot disk image in Google Cloud Platform (GCP)?

easy

A. It stores user data separately from the VM.

B. It provides the operating system for a virtual machine (VM).

C. It manages network traffic for the VM.

D. It controls billing and usage reports.

Solution

1. Step 1: Understand the role of boot disk images

   Boot disk images contain the operating system that a VM uses to start and run.

2. Step 2: Identify the correct function in GCP context

   In GCP, the boot disk image is the source of the OS for the VM instance.

3. Final Answer:

   It provides the operating system for a virtual machine (VM). -> Option B

4. Quick Check:

   Boot disk image = OS provider [OK]

Hint: Boot disk image = OS for VM startup [OK]

Common Mistakes:

• Confusing boot disk image with data disk
• Thinking it manages network or billing
• Assuming it stores user files

2. Which of the following is the correct command to list all available public boot disk images in GCP using gcloud CLI?

easy

A. gcloud compute images list --project=debian-cloud

B. gcloud compute instances list --images

C. gcloud compute disks list --public

D. gcloud compute images list --public

Solution

1. Step 1: Recall the correct gcloud command for listing images

   The command to list images uses 'gcloud compute images list' with a project filter for public images.

2. Step 2: Identify the public image project

   Public images like Debian are under projects such as 'debian-cloud'. So filtering by --project=debian-cloud lists those images.

3. Final Answer:

   gcloud compute images list --project=debian-cloud -> Option A

4. Quick Check:

   List images by project = gcloud compute images list --project=debian-cloud [OK]

Hint: Use --project with public image project name [OK]

Common Mistakes:

• Using --public flag which does not exist
• Listing disks instead of images
• Listing instances instead of images

3. Consider this snippet to create a VM with a boot disk image:

gcloud compute instances create my-vm \
--image-family=ubuntu-2204-lts \
--image-project=ubuntu-os-cloud

What OS will the VM run?

medium

A. Debian 10

B. CentOS 7

C. Ubuntu 22.04 LTS

D. Windows Server 2019

Solution

1. Step 1: Analyze the image family and project

   The image family 'ubuntu-2204-lts' in project 'ubuntu-os-cloud' refers to Ubuntu 22.04 Long Term Support.

2. Step 2: Match image family to OS version

   Ubuntu 22.04 LTS is the latest stable Ubuntu release matching the image family name.

3. Final Answer:

   Ubuntu 22.04 LTS -> Option C

4. Quick Check:

   Image family ubuntu-2204-lts = Ubuntu 22.04 LTS [OK]

Hint: Image family name shows OS version clearly [OK]

Common Mistakes:

• Confusing Ubuntu with Debian or CentOS
• Ignoring image-project parameter
• Assuming Windows from Linux image family

4. You tried to create a VM with this command:

gcloud compute instances create test-vm \
--image-family=centos-7 \
--image-project=centos-cloud \
--boot-disk-size=5GB

The command fails with an error about disk size. What is the likely cause?

medium

A. The VM name 'test-vm' is invalid.

B. The image family name is incorrect.

C. The project name 'centos-cloud' does not exist.

D. The boot disk size is too small for the CentOS 7 image.

Solution

1. Step 1: Understand boot disk size requirements

   CentOS 7 images require a minimum boot disk size larger than 5GB, usually 10GB or more.

2. Step 2: Check command parameters

   The image family and project are correct, and VM name is valid, so the error is due to insufficient disk size.

3. Final Answer:

   The boot disk size is too small for the CentOS 7 image. -> Option D

4. Quick Check:

   Disk size too small causes boot failure [OK]

Hint: Check minimum disk size for image before creating VM [OK]

Common Mistakes:

• Assuming image family or project is wrong
• Ignoring disk size minimum requirements
• Thinking VM name causes disk size error

5. You want to create a custom boot disk image from an existing VM's disk to use for multiple new VMs. Which steps should you follow?

hard

A. Create a snapshot of the VM's boot disk, then create an image from the snapshot.

B. Directly copy the VM instance to create new VMs without images.

C. Export the VM's disk to a local file, then upload it as an image.

D. Create a new VM and select the existing VM's disk as boot disk.

Solution

1. Step 1: Create a snapshot of the existing VM's boot disk

   This captures the current state of the disk safely and efficiently.

2. Step 2: Create a custom image from the snapshot

   Using the snapshot, you create a reusable boot disk image for new VMs.

3. Final Answer:

   Create a snapshot of the VM's boot disk, then create an image from the snapshot. -> Option A

4. Quick Check:

   Snapshot then image = reusable boot disk [OK]

Hint: Snapshot first, then create image for reuse [OK]

Common Mistakes:

• Trying to copy VM directly without image
• Exporting disk unnecessarily
• Using existing disk directly for new VMs