Azure Reserved Instances - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Azure Reserved Instance?

An Azure Reserved Instance is a way to pre-pay for virtual machines for a one- or three-year term to save money compared to pay-as-you-go pricing.

beginner

How does Azure Reserved Instances help with cost management?

By committing to use a virtual machine for a longer time, you get a discount of up to 72% compared to pay-as-you-go prices, helping you save money on cloud costs.

intermediate

Can you change the virtual machine size after buying an Azure Reserved Instance?

Yes, Azure Reserved Instances allow instance size flexibility within the same VM family, so you can switch sizes without losing your reservation benefits.

intermediate

What happens if you stop using a Reserved Instance before the term ends?

You still pay for the full term because you committed to it, but you can exchange or cancel the reservation with some conditions and possible fees.

beginner

What types of Azure resources can you buy Reserved Instances for?

You can buy Reserved Instances for virtual machines, SQL Database compute capacity, Azure Cosmos DB throughput, and other services that support reservations.

What is the main benefit of Azure Reserved Instances?

A Free technical support

B Unlimited resource usage

C Lower cost by pre-paying for resources

D Automatic scaling of resources

Azure Reserved Instances offer cost savings by pre-paying for virtual machines or other resources for a fixed term.

How long can you commit to an Azure Reserved Instance?

A No commitment needed

B 1 month or 6 months

C 5 years only

D 1 year or 3 years

Azure Reserved Instances require a commitment of either 1 year or 3 years.

Can you exchange or cancel an Azure Reserved Instance?

A No, once bought it cannot be changed

B Yes, with some conditions and possible fees

C Yes, anytime without fees

D Only if you upgrade to a bigger VM

Azure allows exchanges or cancellations of Reserved Instances but with conditions and possible fees.

Which of these is NOT a service you can buy Reserved Instances for?

A Azure DevOps Pipelines

B Azure SQL Database compute

C Virtual Machines

D Azure Cosmos DB throughput

Azure DevOps Pipelines is a service but does not support Reserved Instances.

What flexibility do Azure Reserved Instances offer?

A Instance size flexibility within the same VM family

B Use for any Azure service

C Switch regions without restrictions

D Change VM family anytime

Reserved Instances allow instance size flexibility within the same VM family.

Explain what Azure Reserved Instances are and how they help reduce cloud costs.

Think about paying upfront for a discount.

Describe the flexibility and limitations of Azure Reserved Instances regarding changes after purchase.

Consider what you can change and what you cannot.

Practice

1. What is the main benefit of using Azure Reserved Instances?

easy

A. Automatically scale virtual machines up and down

B. Save money by pre-paying for virtual machines

C. Create virtual machines without any cost

D. Backup virtual machines to Azure Storage

Solution

1. Step 1: Understand the purpose of Azure Reserved Instances

   Azure Reserved Instances allow you to pre-pay for virtual machines to get a discount compared to pay-as-you-go pricing.

2. Step 2: Compare options with this purpose

   Only Save money by pre-paying for virtual machines mentions saving money by pre-paying, which matches the main benefit.

3. Final Answer:

   Save money by pre-paying for virtual machines -> Option B

4. Quick Check:

   Reserved Instances = Pre-pay savings [OK]

Hint: Reserved Instances = pre-pay to save money [OK]

Common Mistakes:

• Confusing Reserved Instances with auto-scaling
• Thinking Reserved Instances are free
• Mixing backup features with Reserved Instances

2. Which Azure CLI command is used to purchase a Reserved Instance?

easy

A. az vm create

B. az vm start

C. az storage account create

D. az reservations reservation-order create

Solution

1. Step 1: Identify the CLI command for Reserved Instances

   The Azure CLI command to purchase Reserved Instances is under the 'az reservations' group, specifically 'reservation-order create'.

2. Step 2: Eliminate unrelated commands

   Commands like 'az vm create' create virtual machines, not reservations. 'az vm start' starts VMs, and 'az storage account create' creates storage accounts.

3. Final Answer:

   az reservations reservation-order create -> Option D

4. Quick Check:

   Purchase Reserved Instance = az reservations reservation-order create [OK]

Hint: Reservations commands start with az reservations [OK]

Common Mistakes:

• Using VM creation commands to buy reservations
• Confusing storage commands with reservations
• Trying to start VMs to create reservations

3. Given this Azure CLI command output snippet after buying a Reserved Instance:

{
  "id": "/subscriptions/123/resourceGroups/myRG/providers/Microsoft.Capacity/reservationOrders/abc123",
  "properties": {
    "term": "P1Y",
    "appliedScopeType": "Shared",
    "skuName": "Standard_D2s_v3"
  }
}

What does the "term": "P1Y" mean?

medium

A. The reservation lasts for 1 year

B. The reservation is for 1 month

C. The reservation is for 1 day

D. The reservation is permanent

Solution

1. Step 1: Interpret the term format

   The term 'P1Y' follows ISO 8601 duration format, where 'P' means period and '1Y' means 1 year.

2. Step 2: Match the term to options

   Only The reservation lasts for 1 year correctly states the reservation lasts for 1 year.

3. Final Answer:

   The reservation lasts for 1 year -> Option A

4. Quick Check:

   Term P1Y = 1 year reservation [OK]

Hint: P1Y means period of 1 year in ISO duration [OK]

Common Mistakes:

• Thinking P1Y means 1 month or 1 day
• Assuming term means permanent
• Ignoring ISO 8601 duration format

4. You tried to purchase a Reserved Instance but received an error: "Invalid scope type". What is the likely cause?

medium

A. You specified an unsupported scope type for the reservation

B. You forgot to specify the VM size

C. You used the wrong Azure CLI command

D. Your subscription has no active VMs

Solution

1. Step 1: Understand the error message

   The error 'Invalid scope type' means the scope type parameter for the reservation is not valid or supported.

2. Step 2: Analyze other options

   Missing VM size or wrong CLI command would cause different errors. Having no active VMs does not cause this error.

3. Final Answer:

   You specified an unsupported scope type for the reservation -> Option A

4. Quick Check:

   Invalid scope type error = wrong scope parameter [OK]

Hint: Check scope type parameter when 'Invalid scope type' error appears [OK]

Common Mistakes:

• Assuming missing VM size causes this error
• Using wrong CLI command without checking scope
• Thinking no active VMs cause scope errors

5. You have a steady workload running 4 Standard_D2s_v3 VMs continuously. You want to save costs using Azure Reserved Instances. Which approach is best?

hard

A. Purchase 4 Reserved Instances for different VM sizes

B. Purchase 1 three-year Reserved Instance for Standard_D2s_v3 VM

C. Purchase 4 one-year Reserved Instances for Standard_D2s_v3 VMs

D. Use pay-as-you-go pricing and scale VMs manually

Solution

1. Step 1: Match workload to reservation quantity and term

   You have 4 steady VMs of the same size. Buying 4 Reserved Instances matching the VM size and quantity saves costs.

2. Step 2: Choose appropriate term length

   One-year term is common for steady workloads. Three-year is longer commitment but not required here. Different VM sizes do not match your workload.

3. Final Answer:

   Purchase 4 one-year Reserved Instances for Standard_D2s_v3 VMs -> Option C

4. Quick Check:

   Match VM count and size with Reserved Instances [OK]

Hint: Match Reserved Instances count and size to steady VMs [OK]

Common Mistakes:

• Buying fewer Reserved Instances than VMs
• Choosing wrong VM sizes for reservations
• Ignoring steady workload benefits