How to Resize a VM in Azure: Step-by-Step Guide

To resize a VM in Azure, first stop the VM using az vm deallocate, then resize it with az vm resize specifying the new size, and finally start the VM again with az vm start. This process changes the VM's hardware configuration safely.

Syntax

Use the Azure CLI commands in this order to resize a VM:

• az vm deallocate --resource-group <group> --name <vm-name>: Stops and deallocates the VM to allow resizing.
• az vm resize --resource-group <group> --name <vm-name> --size <new-size>: Changes the VM size.
• az vm start --resource-group <group> --name <vm-name>: Starts the VM with the new size.

Replace <group>, <vm-name>, and <new-size> with your actual resource group, VM name, and desired size.

bash

az vm deallocate --resource-group MyResourceGroup --name MyVM
az vm resize --resource-group MyResourceGroup --name MyVM --size Standard_DS2_v2
az vm start --resource-group MyResourceGroup --name MyVM

Example

This example shows how to resize a VM named MyVM in the resource group MyResourceGroup to size Standard_DS2_v2. It stops the VM, resizes it, then starts it again.

bash

az vm deallocate --resource-group MyResourceGroup --name MyVM
az vm resize --resource-group MyResourceGroup --name MyVM --size Standard_DS2_v2
az vm start --resource-group MyResourceGroup --name MyVM

Output

Deallocating VM 'MyVM'...
VM 'MyVM' deallocated.
Resizing VM 'MyVM' to size 'Standard_DS2_v2'...
VM 'MyVM' resized.
Starting VM 'MyVM'...
VM 'MyVM' started.

Common Pitfalls

Common mistakes when resizing Azure VMs include:

• Trying to resize while the VM is running. The VM must be stopped and deallocated first.
• Choosing a VM size not supported in the VM's region or subscription.
• Not verifying if the new size is compatible with the VM's OS disk or attached resources.

Always check available sizes with az vm list-sizes --location <region> before resizing.

bash

## Wrong: resizing while VM is running
az vm resize --resource-group MyResourceGroup --name MyVM --size Standard_DS2_v2

## Right: stop first, then resize
az vm deallocate --resource-group MyResourceGroup --name MyVM
az vm resize --resource-group MyResourceGroup --name MyVM --size Standard_DS2_v2
az vm start --resource-group MyResourceGroup --name MyVM

Quick Reference

Command	Purpose
az vm deallocate --resource-group --name	Stop and deallocate the VM to allow resizing
az vm resize --resource-group --name --size	Change the VM size
az vm start --resource-group --name	Start the VM with the new size
az vm list-sizes --location	List available VM sizes in a region

Key Takeaways

Always stop and deallocate the VM before resizing to avoid errors.

Use the Azure CLI commands: deallocate, resize, then start the VM.

Verify the new VM size is available in your region before resizing.

Resizing changes the VM's hardware specs but keeps your data intact.

Check compatibility of the new size with your VM's OS and attached disks.