We are in the transitioning phase from an old flavor naming format to a new one, and this creates the need for all existing VM's to be migrated to the new flavors. There are already an article on which flavors to migrate to HERE and a description of the new naming format is found HERE. This article guides you through the migration-process for either the CLI or the web-interface.

Using the Openstack Horizon web interface

Instance overview

When looking on your instance overview in horizon you should normally be able to see which flavor a certain instance is. In this picture you can see that the instance "ResizeDemo" is of the flavor "t1.large".

If the flavor you are using is unavailable to your project, for instance because the flavor is disabled or not public anymore, horizon will list "Not Available" instead.

Starting the resize of an instance

To actually resize an instance you need to click the small button with the triangle in it to see all actions you can perform on the instance, and select the action "Resize Instance". This button is red to signalize to you that this action will affect the services in your virtual machine, as it reboots it. After selecting the "Resize Instance" button you get a dialog-box showing what flavor your VM have (and here the flavor is shown by name even though it was not visible in the overview) and you can select what flavor you want it to have. The recommended upgrade for a t1.large is in stackit "gx2.2c1r", so that is selected in this example:

Clicking the "Resize" button will stop your VM before it is restarted with the specifications from the new flavor.

Finalizing the resize

After a VM is resized openstack want you to check that it works before it is releasing the resources the VM had before the resize. In the overview you can see this status as "Confirm or Revert":

Clicking the "Confirm Resize/Migrate" button will place your VM in the regular "Active" state, and your migration to the new flavors is completed for this VM.

Using the command line client (CLI) 

Instance overview

Usually the flavor of a certain instance is visible in the VM overview:

If the flavor you are using is unavailable to your project, for instance because the flavor is disabled or not public anymore, the overview will not list the flavor for a certain instance:

You can however see the flavor for a single instance with the "openstack server show" command.

Resize the VM:

Performing the resize of a VM using the CLI is a two-step approach. First you use the "openstack server resize" command to start the resizing, and when the server is resized you need to confirm it using the "openstack server resize confirm" command. Using "openstack server show" lets you see a servers status as you go; and the resizing of a server using CLI might thus look like so: