VM sizes and series (B, D, E, F) in Azure - Commands & Configuration

Introduction

Choosing the right virtual machine size helps your app run smoothly without wasting money. Azure offers different VM series with varying power and cost to fit different needs.

When you want a low-cost VM that can handle occasional bursts of activity without paying for full power all the time.

When you need a balanced VM for general purpose tasks like web servers or small databases.

When your app requires more memory for faster data processing or caching.

When you need a VM optimized for compute-heavy tasks like batch processing or gaming servers.

Commands

This command lists all available VM sizes in the East US region so you can see options like B, D, E, and F series.

Terminal

az vm list-sizes --location eastus

Expected Output

[{"name":"Standard_B1s","numberOfCores":1,"memoryInMb":1024,"maxDataDiskCount":2,"osDiskSizeInMb":1047552,"resourceDiskSizeInMb":4096,"maxNicCount":2},{"name":"Standard_D2s_v3","numberOfCores":2,"memoryInMb":8192,"maxDataDiskCount":4,"osDiskSizeInMb":1047552,"resourceDiskSizeInMb":16384,"maxNicCount":2},{"name":"Standard_E2s_v3","numberOfCores":2,"memoryInMb":16384,"maxDataDiskCount":4,"osDiskSizeInMb":1047552,"resourceDiskSizeInMb":16384,"maxNicCount":2},{"name":"Standard_F2s_v2","numberOfCores":2,"memoryInMb":4096,"maxDataDiskCount":4,"osDiskSizeInMb":1047552,"resourceDiskSizeInMb":16384,"maxNicCount":2}]

→

--location - Specifies the Azure region to list VM sizes available there.

Creates a VM using the B1s size, which is a low-cost burstable VM good for light workloads with occasional spikes.

Terminal

az vm create --resource-group example-rg --name example-vm --image UbuntuLTS --size Standard_B1s --admin-username azureuser --generate-ssh-keys

Expected Output

{

  "fqdns": "",

  "id": "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/example-rg/providers/Microsoft.Compute/virtualMachines/example-vm",

  "location": "eastus",

  "name": "example-vm",

  "powerState": "VM running",

  "resourceGroup": "example-rg",

  "zones": []

}

→

--size - Specifies the VM size to use.

→

--generate-ssh-keys - Automatically creates SSH keys for secure login.

Checks the size of the VM to confirm it was created with the correct series and size.

Terminal

az vm show --resource-group example-rg --name example-vm --query hardwareProfile.vmSize

Expected Output

"Standard_B1s"

→

--query - Filters output to show only the VM size.

Key Concept

If you remember nothing else from this pattern, remember: choose the VM size series that matches your workload needs for cost and performance balance.

Common Mistakes

Choosing a VM size without checking if it is available in the desired region.

The VM size might not be offered in that region, causing deployment failure.

Always run 'az vm list-sizes --location your-region' to confirm availability before creating a VM.

Using a high-powered VM size for a light workload.

This wastes money because you pay for more resources than needed.

Pick a smaller or burstable VM size like B series for light or variable workloads.

Summary

Use 'az vm list-sizes' to see available VM sizes in your region.

Create VMs with the '--size' flag to pick the right series like B, D, E, or F.

Verify your VM size after creation to ensure it matches your needs.

Practice

1. Which Azure VM series is best suited for applications that need to handle occasional spikes in CPU usage but are idle most of the time?

easy

A. E series (memory optimized)

B. D series (balanced CPU and memory)

C. B series (burstable VMs)

D. F series (compute optimized)

Solution

1. Step 1: Understand the purpose of B series VMs

   B series VMs are designed for workloads that are idle most of the time but need to burst CPU power occasionally.

2. Step 2: Compare with other series

   D series are balanced, E series focus on memory, and F series focus on CPU but not burstable. So B series fits the description best.

3. Final Answer:

   B series (burstable VMs) -> Option C

4. Quick Check:

   Bursty CPU needs = B series [OK]

Hint: Burstable CPU needs? Pick B series [OK]

Common Mistakes:

• Choosing D series for bursty workloads
• Confusing F series with burstable
• Picking E series which is memory optimized

2. Which of the following is the correct way to describe the F series Azure VMs?

easy

A. Memory optimized VMs for heavy database workloads

B. Burstable VMs for low baseline CPU usage

C. Balanced VMs with equal CPU and memory

D. Compute optimized VMs with higher CPU-to-memory ratio

Solution

1. Step 1: Identify F series characteristics

   F series VMs are compute optimized, meaning they have more CPU power relative to memory.

2. Step 2: Eliminate other options

   Memory optimized describes E series, burstable describes B series, and balanced describes D series.

3. Final Answer:

   Compute optimized VMs with higher CPU-to-memory ratio -> Option D

4. Quick Check:

   F series = compute optimized [OK]

Hint: F series means more CPU power, less memory [OK]

Common Mistakes:

• Mixing F series with memory optimized E series
• Thinking F series are burstable
• Confusing balanced D series with F series

3. You deploy an application that requires high memory but moderate CPU. Which VM series will likely give you the best performance and cost balance?
Options: B, D, E, F

medium

A. B series

B. E series

C. F series

D. D series

Solution

1. Step 1: Match workload needs to VM series

   High memory and moderate CPU needs point to memory optimized VMs.

2. Step 2: Identify E series as memory optimized

   E series VMs are designed for memory-intensive workloads, making them suitable here.

3. Final Answer:

   E series -> Option B

4. Quick Check:

   High memory need = E series [OK]

Hint: High memory? Choose E series [OK]

Common Mistakes:

• Choosing F series which is CPU optimized
• Picking B series which is burstable
• Selecting D series which is balanced but not memory focused

4. A developer chose a B series VM for a high-CPU, always-on web server. What is the main issue with this choice?

medium

A. B series VMs are burstable and may throttle CPU under constant load

B. B series VMs do not support web servers

C. B series VMs have too much memory for web servers

D. B series VMs are more expensive than F series

Solution

1. Step 1: Understand B series limitations

   B series VMs are designed for workloads with low baseline CPU and occasional bursts, not constant high CPU.

2. Step 2: Identify why this is a problem for always-on high CPU

   Constant high CPU usage will cause B series VMs to throttle performance, hurting the web server.

3. Final Answer:

   B series VMs are burstable and may throttle CPU under constant load -> Option A

4. Quick Check:

   Constant high CPU ≠ B series [OK]

Hint: Burstable VMs throttle under constant CPU load [OK]

Common Mistakes:

• Thinking B series can't run web servers
• Assuming B series has too much memory
• Believing B series is more expensive than F series

5. You need to deploy a data analytics application that requires high CPU power and large memory but must also be cost-effective. Which VM series combination should you consider to optimize performance and cost?

hard

A. Use F series for CPU-intensive tasks and E series for memory-intensive tasks

B. Use only B series VMs to save cost

C. Use D series VMs as they balance CPU and memory well

D. Use E series only because memory is most important

Solution

1. Step 1: Analyze workload requirements

   The application needs both high CPU and large memory, which may not be met efficiently by a single VM series.

2. Step 2: Consider splitting workload across VM series

   F series VMs provide high CPU power, while E series VMs provide large memory. Using both can optimize cost and performance.

3. Step 3: Evaluate other options

   B series is burstable and not suitable for heavy workloads. D series is balanced but may not optimize cost as well. E series alone may lack CPU power.

4. Final Answer:

   Use F series for CPU-intensive tasks and E series for memory-intensive tasks -> Option A

5. Quick Check:

   Split CPU and memory needs = F + E series [OK]

Hint: Split CPU and memory tasks across F and E series [OK]

Common Mistakes:

• Choosing only B series to save cost ignoring performance
• Relying solely on D series without optimization
• Using only E series and missing CPU needs