AzureHow-ToBeginner · 4 min read

How to Choose VM Size in Azure: A Simple Guide

To choose a VM size in Azure, consider your workload's CPU, memory, storage, and network needs. Use Azure's VM size families and the Azure Pricing Calculator to match your requirements with available options and budget.

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Syntax

Azure VM sizes follow a naming pattern that indicates their family and capabilities. The general format is:

<Family><Number>_v<Version>
Family: Indicates the VM type optimized for specific workloads (e.g., D for general purpose, E for memory optimized).
Number: Represents the size within the family (higher means more resources).
Version: The generation of the VM size.

Example: D4_v3 means a general purpose VM, size 4, version 3.

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VM Size Format: <Family><Number>_v<Version>

Examples:
D2_v3  # General purpose, size 2, version 3
E8_v4  # Memory optimized, size 8, version 4
F16s_v2 # Compute optimized, size 16, version 2

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Example

This example shows how to select a VM size for a web application that needs moderate CPU and memory but low cost.

bash

az vm list-sizes --location eastus --output table

Output

Name NumberOfCores MemoryInMb MaxDataDiskCount Standard_B1s 1 1024 2 Standard_B2s 2 4096 4 Standard_D2s_v3 2 8192 8 Standard_D4s_v3 4 16384 16

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Common Pitfalls

Common mistakes when choosing Azure VM sizes include:

Choosing a VM size without considering the workload type, leading to wasted resources or poor performance.
Ignoring regional availability, as some VM sizes are not available in all Azure regions.
Not factoring in cost differences between VM sizes and families.
Overlooking the need for premium storage support if your workload requires it.

Always check the Azure VM pricing page and region availability before finalizing your choice.

bash

Wrong way:
az vm create --name myVM --resource-group myRG --image UbuntuLTS --size Standard_D16s_v3

Right way:
az vm create --name myVM --resource-group myRG --image UbuntuLTS --size Standard_D4s_v3
# Choose size based on actual CPU and memory needs to save cost

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Quick Reference

VM Family	Use Case	Key Features
B-series	Burstable workloads	Low cost, variable CPU performance
D-series	General purpose	Balanced CPU and memory
E-series	Memory optimized	High memory-to-CPU ratio
F-series	Compute optimized	High CPU-to-memory ratio
L-series	Storage optimized	High disk throughput and IOPS
N-series	GPU optimized	Graphics and compute intensive tasks

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Key Takeaways

Match VM size family to your workload type for best performance and cost.

Check VM size availability in your Azure region before deployment.

Use Azure CLI or portal to list and compare VM sizes and specs.

Consider CPU, memory, storage, and network needs together.

Use Azure Pricing Calculator to estimate costs before choosing.