Edit the machine type of a VM instance

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If your VM does not have a local SSD and is not part of a managed instance group (MIG), you can change the machine type of your VM after stopping it.

If your existing machine type is not a good fit for the workloads you run on your VM, change the machine type of that VM. You can change the machine type of a VM to adjust the number of vCPUs and memory as your workload changes. For example, you can start a VM with a smaller machine during setup, development, and testing and change the VM to use a larger machine type when you are ready for production workloads.

For VMs that do not have a local SSD and are not part of a MIG, you can change the machine type without affecting the following resources:

  • The VM's SSH keys
  • The VM configurations, such as VM metadata
  • The VM's persistent disk data, including installed applications and application data

If you need to change the machine type of VMs within a MIG, read about updating MIGs.

If your VM has a local SSD, you cannot stop the VM to change its machine type unless you force it to stop, which causes you to lose all of the data on the local SSD. For details, see Adding local SSDs.

Before you begin

Billing implications

Each machine type is billed at a different rate, so make sure you understand the pricing implications of changing machine types. For example, an e2-standard-2 machine type costs more than an e2-micro machine type.

Changing a machine type might also affect the sustained use discounts for that VM. Sustained use discounts are calculated separately for different categories in the same region. If you change machine types so that the new machine type is in a different category, the subsequent running time of the VM counts toward the sustained use discount of the new category.

For example, assume you have a VM with n2-standard-2 machine type running for half a month. You then decide to change the machine type to m1-ultramem-40. Once you make that change, Compute Engine starts counting the running time of the VM towards the sustained use discount of the memory-optimized vCPU and memory category.

On your bill, you would see a sustained use discount applied to the n2-standard-2 machine type from before you made the machine type change, and a separate sustained use discount for m1-ultramem-40, if your VM remains running on m1-ultramem-40 for at least a 25% of the rest of the month.

Best practices

Here are some best practices to help you successfully change the VM machine type.

  • Make regular backups of your persistent disk data using snapshots. Consider taking a snapshot of your persistent disk data before you change the machine type. If you want to make sure the new machine type is able to support the data on the existing VM, you can take a persistent disk snapshot and use it to start a second VM with the new machine type to confirm that the VM starts up successfully.

  • Add additional persistent disks to the /etc/fstab file. If you have additional persistent disks attached to your VM, make sure they are added to the /etc/fstab file so that they are automatically mounted when the VM reboots.

  • Create a reservation before changing the machine type. To avoid errors related to resource availability, create Compute Engine reservations for the new machine types when they are available to reserve them within a zone. Reservations help ensure that the resources are available when you need them.

To create a reservation, complete the following steps:

  1. Create a reservation (or identify existing reservations) with identical properties as the planned VMs. The reservation's VM count needs to be equal to or greater than the number of VMs that you want to change. Optionally, to prevent other VMs from consuming this reservation, use the specificReservationRequired option.

  2. Verify that the planned VMs will be able to consume the reservation:

    1. Verify that the desired VMs have the correct reservation affinity.
    2. Immediately before changing the VMs, ensure the reservation has enough capacity.

Change a machine type

You can only change the machine type of a stopped VM. A VM is considered stopped only when the VM is in the TERMINATED state. You cannot change the machine type of a running VM.

If you are upgrading your machine type to the latest generation, review Migrate to third generation machine series before proceeding.

Permissions required for this task

To perform this task, you must have the following permissions:

  • compute.instances.setMachineType on the VM

Console

  1. In the Google Cloud console, go to the VM instances page.

    Go to VM instances

  2. In the Name column, click the name of the VM for which you want to change machine type.

  3. From the VM instance details page, complete the following steps:

    1. If the VM is running, click Stop to stop the VM.
    2. To edit the VM, click Edit.
    3. In the Machine configuration section, select the machine type that you want to use, or create a custom machine type.

    4. To save your changes, click Save.

gcloud

  1. Stop the VM by using the gcloud compute instances stop command:

    gcloud compute instances stop VM_NAME
    

    Replace VM_NAME with the VM containing the machine type to change.

  2. Change the machine type by using the gcloud compute instances set-machine-type command:

    gcloud compute instances set-machine-type VM_NAME \
        --machine-type NEW_MACHINE_TYPE
    

    Replace NEW_MACHINE_TYPE with the new machine type for the VM. The machine type can be one of the following:

API

  1. Stop the VM by using the instances.stop method:

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME/stop
    

    Replace the following:

    • PROJECT_ID: the project ID

    • ZONE: the zone containing the VM

    • VM_NAME: the VM containing the machine type to change

  2. Change the machine type by using the instances.setMachineType method:

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME/setMachineType
    

    In the body of the request, provide the updated machineType:

    {
        machineType: "zones/MACHINE_TYPE_ZONE/machineTypes/NEW_MACHINE_TYPE"
    }
    

    Replace the following:

    • MACHINE_TYPE_ZONE: the zone containing the machine type

    • NEW_MACHINE_TYPE: the new machine type for the VM

      The machine type can be one of the following:

Move to a smaller machine type

If you move from a machine type with more resources to a machine type with fewer resources, such as moving from a e2-standard-8 machine type to a e2-standard-2, you could run into hardware resource issues or performance limitations because smaller machine types are less powerful than larger machine types. Make sure that your new machine type is able to support any applications or services that are currently running on the VM, or that you update your services and applications to run on the smaller machine types.

Review the rightsizing recommendations before changing the machine type. For information about Compute Engine sizing recommendations, see Applying machine type recommendations for VM instances.

Migrate to a third generation machine series

When the requirements are met, you can use a new generation VM in a machine series by changing the machine type—for example, from m1-ultramem-160 to m3-ultramem-128.

Newer generation machine types might not support the same features and interfaces as your current machine type. Before starting the migration process, review the machine type information for the newer generation–for example, M3.

The new machine type might not be available in all the same regions and zones as your current VM instance. Review the available regions and zones for the newer generation machine series, and adjust your disaster recovery plans as needed.

To change the machine type for your VM instance to a third generation machine type, you can use either of the following approaches.

Create and migrate to a new VM instance

In this procedure, you create a new VM instance, then move your workload to the new VM.

For details on how to complete this procedure, see Migrate your workload from an existing VM to a new VM.

Change the machine type to a new machine type

In this procedure, you verify that your current VM instance can be updated to use the new machine type, and then change the machine type.

  1. Verify your current VM instance uses a supported operating system version. If the version is not supported, then follow Migrate your workload from an existing VM to a new VM.

  2. Verify your applications and programs can support a different network or storage interface, such as gVNIC or NVMe.

  3. Save the image to the boot disk.

  4. Follow the procedure described in Change a machine type.

What's next