Resizing a virtual machine using OpenStack CLI on 3Engines Cloud[πŸ”—](#resizing-a-virtual-machine-using-openstack-cli-on-brand-name "Permalink to this headline") ================================================================================================================================================================= Introduction[πŸ”—](#introduction "Permalink to this headline") ----------------------------------------------------------- When creating a new virtual machine under OpenStack, one of the options you choose is the *flavor*. A flavor is a predefined combination of CPU, memory and disk size and there usually is a number of such flavors for you to choose from. After the instance is spawned, it is possible to change one flavor for another, and that process is called *resizing*. You might want to resize an already existing VM in order to: > * increase (or decrease) the number of CPUs used, > * use more RAM to prevent crashes or enable swapping, > * add larger storage to avoid running out of disk space, > * seamlessly transition from testing to production environment, > * change application workload byt scaling the VM up or down. In this article, we are going to resize VMs using CLI commands in OpenStack. Prerequisites[πŸ”—](#prerequisites "Permalink to this headline") ------------------------------------------------------------- No. 1 **Account** You need a 3Engines Cloud hosting account with access to the Horizon interface: . If you are a normal user of 3Engines Cloud hosting, you will have all prerogatives needed to resize the VM. Make sure that the VM you are about to resize belongs to a project you have access to. [How to create a VM using the OpenStack CLI client on 3Engines Cloud cloud](../cloud/How-to-create-a-VM-using-the-OpenStack-CLI-client-on-3Engines-Cloud-cloud.html.md) No. 2 **Awareness of existing quotas and flavors limits** For general introduction to quotas and flavors, see [Dashboard Overview – Project Quotas And Flavors Limits on 3Engines Cloud](../cloud/Dashboard-Overview-Project-Quotas-And-Flavors-Limits-on-3Engines-Cloud.html.md). Also: > * The VM you want to resize is in an active or shut down state. > * A flavor with the desired resource configuration exists. > * Adequate resources are available in your OpenStack environment to accommodate the resize. Creating a new VM[πŸ”—](#creating-a-new-vm "Permalink to this headline") --------------------------------------------------------------------- To illustrate the commands in this article, let us create a new VM in order to start with a clean slate. (It goes without saying that you can practice with any of the already existing VMs in your account.) To see all flavors: ``` openstack flavor list ``` ![resize-vm-horizon-cli-3.png](../_images/resize-vm-horizon-cli-3.png) This is the command to create a new VM called **ResizingCLI**: ``` openstack server create \ --image "Ubuntu 22.04 LTS" \ --flavor eo2a.large \ --key-name sshkey \ --network cloud_00341_3 \ --security-group default \ --security-group allow_ping_ssh_icmp_rdp \ ResizingCLI ``` This is the result: ![resize-vm-horizon-cli-2.png](../_images/resize-vm-horizon-cli-2.png) The **id** for **ResizingCLI** is **82bba971-8ff1-4f85-93d6-9d56bb7b185d** and we can use it in various commands to denote this particular VM. To see all currently available VMs, use command ``` openstack server list ``` Steps to Resize the VM[πŸ”—](#steps-to-resize-the-vm "Permalink to this headline") ------------------------------------------------------------------------------- To resize a VM with CLI, there is a general command ``` openstack server resize --flavor ``` We need flavor ID or name as well as VM’s name or id. In this example we want to scale up the existing VM **ResizingCLI**, using **eo2.xlarge** flavor. The command will be: ``` openstack server resize --flavor eo2.xlarge ResizingCLI ``` To verify the resize, check the status of the VM: ``` openstack server show ResizingCLI ``` ![resize-vm-horizon-cli-4.png](../_images/resize-vm-horizon-cli-4.png) When the VM has **VERIFY\_RESIZE** status, we are able to confirm the resize. The command is: ``` openstack server resize confirm ResizingCLI ``` Execute once again: ``` openstack server show ResizingCLI ``` to see the real state of the VM after confirmation. We will now see that the **status** is **ACTIVE**. Reverting a resize[πŸ”—](#reverting-a-resize "Permalink to this headline") ----------------------------------------------------------------------- Reverting a resize switches the VM back to its original flavor and cleans up temporary resources allocated during the resize operation. It is only possible to revert a resize if the status is **VERIFY\_RESIZE**. The command would be: ``` openstack server resize revert ResizingCLI ``` If status is not **VERIFY\_RESIZE**, we will get message stating that it is not possible to revert resize while it is in an active state (HTTP 409). In that case, perform the β€œregular” resizing with **openstack server resize**. What To Do Next[πŸ”—](#what-to-do-next "Permalink to this headline") ----------------------------------------------------------------- You can also resize the virtual machine using only OpenStack CLI. More details here: /openstackcli/Resizing-a-virtual-machine-using-OpenStack-Horizon-on-3Engines-Cloud