Resize an instance

Find out how to resize an instance in the Horizon interface

Last updated 22nd November 2021


As a result of increased activity, or simply new needs, your instance may not be able to meet this new burden due to a lack of resources. However, with the Public Cloud, you can increase the resources available to your instance, and this can be done with just a few clicks.

This guide will show you how to resize your instance using the OpenStack Horizon interface.

Only upscaling is possible for classic models. In addition, this manipulation causes the instance to be shut down for the time of the operation.

Flex instances allow resizing to higher or lower models due to a locked single disk size.



Log into the Horizon interface, and make sure you are in the correct region. You can verify this on the top left corner.

Next, click on the Compute menu on the left side and select Instances. Select Resize Instance in the drop list for the corresponding instance.

Resize instance

Template Selection Tab (Flavor Choice)

This section shows the current template (old flavor) and allows you to select a new template (new flavor) for the instance resource.


Flavor Details

In this section, you will see the resources associated with the new template you have chosen.

Project Limits

Under this section, you can view the occupied resources in relation to the total resources allocated to the project.

Please note that you cannot switch models when resizing an instance. A resizing can only be done from a Linux model to another Linux model or from a Windows model to another Windows model.

Advanced Options

Use this section to manage the Disk Partition and Server Group.


Once the configuration is complete, click on Resize.

Resizing a disk in Windows

When performing a resize for a Windows Instance, please note that the partition size is not automatically updated, so you will have to extend it using the disk manager:

  • Right-click on the Start menu and launch the disk manager by clicking on Disk Management:


  • Right-click on the main partition, then click on Extend Volume.


  • In the Extend Volume Wizard menu, click on Next to proceed. In the next tab, choose the disk resources to extend and click on Next.


Once done, click on Finish to confirm your choice.


  • The new disk size will then be displayed in the disk manager.


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