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Edit the configuration of a virtual machine

You can update virtual machine (VM) configuration details like CPU, memory, and networking by using the CLI or the OpenShift Container Platform web console. In the web console, you can modify settings on the VirtualMachine details page or by editing the YAML file directly.

To edit a VM to configure disk sharing by using virtual disks or LUN, see "Configuring shared volumes for virtual machines".

Changing the instance type of a VM by using the web console​

You can change the instance type associated with a running virtual machine (VM) by using the web console. The change takes effect immediately.

Prerequisites

  • You created the VM by using an instance type.

Procedure

  1. In the OpenShift Container Platform web console, click Virtualization → VirtualMachines.
  2. Select a VM to open the VirtualMachine details page.
  3. Click the Configuration tab.
  4. On the Details tab, click the instance type text to open the Edit Instancetype dialog. For example, click 1 CPU | 2 GiB Memory.
  5. Edit the instance type by using the Series and Size lists.
    1. Select an item from the Series list to show the relevant sizes for that series. For example, select General Purpose.
    2. Select the new instance type for the VM from the Size list. For example, select medium: 1 CPUs, 4Gi Memory, which is available in the General Purpose series.
  6. Click Save.

Verification

  1. Click the YAML tab.
  2. Click Reload.
  3. Review the VM YAML to confirm that the instance type changed.

Hot plugging memory on a virtual machine​

You can add or remove the amount of memory allocated to a virtual machine (VM) without having to restart the VM by using the OpenShift Container Platform web console.

Procedure

  1. Navigate to Virtualization → VirtualMachines.

  2. Select the required VM to open the VirtualMachine details page.

  3. On the Configuration tab, click Edit CPU|Memory.

  4. Enter the required amount of memory and click Save.

    note

    By hot plugging, you can increase the total amount of memory of a VM up to four times the default initial amount. Exceeding this limit requires a restart.

    The system applies these changes immediately. If the VM is able to be migrated, a live migration is triggered. If not, or if the changes cannot be live-updated, a RestartRequired condition is added to the VM.

    note

    Memory hot plugging for virtual machines requires guest operating system support for the virtio-mem driver. This support depends on the driver being included and enabled within the guest operating system, not on specific upstream kernel versions.

    Supported guest operating systems:

    • RHEL 9.4 and later
    • RHEL 8.10 and later (hot-unplug is disabled by default)
    • Other Linux guests require kernel version 5.16 or later and the virtio-mem kernel module
    • Windows guests require virtio-mem driver version 100.95.104.26200 or later

Hot plugging CPUs on a virtual machine​

You can increase or decrease the number of CPU sockets allocated to a virtual machine (VM) without having to restart the VM by using the OpenShift Container Platform web console.

Procedure

  1. Navigate to Virtualization → VirtualMachines.

  2. Select the required VM to open the VirtualMachine details page.

  3. On the Configuration tab, click Edit CPU|Memory.

  4. Select the vCPU radio button.

  5. Enter the required number of vCPU sockets and click Save.

    note

    By hot plugging, you can increase the total number of vCPU sockets of a VM up to four times the default initial number. Exceeding this limit requires a restart.

    If the VM is migratable, a live migration is triggered. If not, or if the changes cannot be live-updated, a RestartRequired condition is added to the VM.

    note

    If a VM has the spec.template.spec.domain.devices.networkInterfaceMultiQueue field enabled and CPUs are hot plugged, the following behavior occurs:

    • Existing network interfaces that you attach before the CPU hot plug retain their original queue count, even after you add more virtual CPUs (vCPUs). The underlying virtualization technology causes this expected behavior.
    • To update the queue count of existing interfaces to match the new vCPU configuration, you can restart the VM. A restart is only necessary if the update improves performance.
    • New VirtIO network interfaces that you hot plugged after the CPU hot plug automatically receive a queue count that matches the updated vCPU configuration.

Editing a virtual machine by using the CLI​

You can edit a virtual machine (VM) by using the command line.

Prerequisites

  • You installed the oc CLI.

Procedure

  1. Obtain the virtual machine configuration by running the following command: 
    $ oc edit vm <vm_name>
  2. Edit the YAML configuration.
  3. If you edit a running virtual machine, you need to do one of the following:
    • Restart the virtual machine.
    • Run the following command for the new configuration to take effect: 
      $ oc apply vm <vm_name> -n <namespace>

Adding a disk to a virtual machine​

You can add a virtual disk to a virtual machine (VM) by using the OpenShift Container Platform web console.

Procedure

  1. Navigate to Virtualization → VirtualMachines in the web console.

  2. Select a VM to open the VirtualMachine details page.

  3. On the Disks tab, click Add disk.

  4. Specify the Source, Name, Size, Type, Interface, and Storage Class.

    1. Optional: You can enable preallocation if you use a blank disk source and require maximum write performance when creating data volumes. To do so, select the Enable preallocation checkbox.
    2. Optional: You can clear Apply optimized StorageProfile settings to change the Volume Mode and Access Mode for the virtual disk. If you do not specify these parameters, the system uses the default values from the kubevirt-storage-class-defaults config map.

  5. Click Add.

    note

    If the VM is running, you must restart the VM to apply the change.

Storage fields​

To optimize storage performance and ensure data availability for your workloads, configure the storage fields to define the source, size, and disk characteristics of your virtual machine (VM).

Field Description
Blank (creates PVC) Create an empty disk.
Import via URL (creates PVC) Import content via URL (HTTP or HTTPS endpoint).
Use an existing PVC Use a PVC that is already available in the cluster.
Clone existing PVC (creates PVC) Select an existing PVC available in the cluster and clone it.
Import via Registry (creates PVC) Import content via container registry.
Container (ephemeral) Upload content from a container located in a registry accessible from the cluster. The container disk should be used only for read-only filesystems such as CD-ROMs or temporary virtual machines.
Name Name of the disk. The name can contain lowercase letters (a-z), numbers (0-9), hyphens (-), and periods (.), up to a maximum of 253 characters. The first and last characters must be alphanumeric. The name must not contain uppercase letters, spaces, or special characters.
Size Size of the disk in GiB.
Type Type of disk. Example: Disk or CD-ROM
Interface Type of disk device. Supported interfaces are virtIO, SATA, and SCSI.
Storage Class The storage class that is used to create the disk.

Advanced storage settings​

The following advanced storage settings are optional and available for Blank, Import via URL, and Clone existing PVC disks.

If you do not specify these parameters, the system uses the default storage profile values.

Parameter Option Parameter description
Volume Mode Filesystem Stores the virtual disk on a file system-based volume.
Block Stores the virtual disk directly on the block volume. Only use Block if the underlying storage supports it.
Access Mode ReadWriteOnce (RWO) Volume can be mounted as read/write by a single node.
ReadWriteMany (RWX) Volume can be mounted as read/write by many nodes at one time.
Note

This mode is required for live migration.

ReadOnlyMany (ROX) Volume can be mounted as read only by many nodes.

Note

ReadWriteMany access mode is required for live migration.

Mounting a Windows driver disk on a virtual machine​

You can mount a Windows driver disk on a virtual machine (VM) by using the OpenShift Container Platform web console.

Procedure

  1. Navigate to Virtualization → VirtualMachines.
  2. Select the required VM to open the VirtualMachine details page.
  3. On the Configuration tab, click Storage.
  4. Select the Mount Windows drivers disk checkbox. The Windows driver disk is displayed in the list of mounted disks.

Adding a secret, config map, or service account to a virtual machine​

You can add a secret, config map, or service account to a virtual machine by using the OpenShift Container Platform web console.

These resources are added to the virtual machine as disks. You then mount the secret, config map, or service account as you would mount any other disk.

If the virtual machine is running, changes do not take effect until you restart the virtual machine. The newly added resources are marked as pending changes at the top of the page.

Prerequisites

  • The secret, config map, or service account that you want to add must exist in the same namespace as the target virtual machine.

Procedure

  1. Click Virtualization → VirtualMachines from the side menu.
  2. Select a virtual machine to open the VirtualMachine details page.
  3. Click Configuration → Environment.
  4. Click Add Config Map, Secret or Service Account.
  5. Click Select a resource and select a resource from the list. A six character serial number is automatically generated for the selected resource.
  6. Optional: Click Reload to revert the environment to its last saved state.
  7. Click Save.

Verification

  1. On the VirtualMachine details page, click Configuration → Disks and verify that the resource is displayed in the list of disks.
  2. Restart the virtual machine by clicking Actions → Restart.

You can now mount the secret, config map, or service account as you would mount any other disk.

Updating multiple virtual machines​

You can use the command line interface (CLI) to update multiple virtual machines (VMs) at the same time.

Prerequisites

  • You installed the OpenShift CLI (oc).
  • You have access to the OpenShift Container Platform cluster, and you have cluster-admin permissions.

Procedure

  1. Create a privileged service account by running the following commands:

    $ oc adm new-project kubevirt-api-lifecycle-automation
    $ oc create sa kubevirt-api-lifecycle-automation -n kubevirt-api-lifecycle-automation
    $ oc create clusterrolebinding kubevirt-api-lifecycle-automation --clusterrole=cluster-admin --serviceaccount=kubevirt-api-lifecycle-automation:kubevirt-api-lifecycle-automation

  2. Determine the pull URL for the kubevirt-api-lifecycle image by running the following command:

    $ oc get csv -n openshift-cnv -l=operators.coreos.com/kubevirt-hyperconverged.openshift-cnv -ojson | jq '.items[0].spec.relatedImages[] | select(.name|test(".*kubevirt-api-lifecycle-automation.*")) | .image'

  3. Deploy Kubevirt-Api-Lifecycle-Automation by creating a job object as shown in the following example:

    apiVersion: batch/v1
    kind: Job
    metadata:
     name: kubevirt-api-lifecycle-automation
     namespace: kubevirt-api-lifecycle-automation
    spec:
     template:
      spec:
       containers:
       - name: kubevirt-api-lifecycle-automation
         image: quay.io/openshift-virtualization/kubevirt-api-lifecycle-automation:v4.22
         imagePullPolicy: Always
         env:
         - name: MACHINE_TYPE_GLOB
           value: smth-glob9.10.0
         - name: RESTART_REQUIRED
           value: "true"
         - name: NAMESPACE
           value: "default"
         - name: LABEL_SELECTOR
           value: my-vm
         securityContext:
          allowPrivilegeEscalation: false
          capabilities:
           drop:
           - ALL
          privileged: false
          runAsNonRoot: true
          seccompProfile:
           type: RuntimeDefault
       restartPolicy: Never
       serviceAccountName: kubevirt-api-lifecycle-automation

    where:

    quay.io/openshift-virtualization/kubevirt-api-lifecycle-automation:v4.22
    Specifies the pull URL for your image. Replace the image value in this example with your pull URL for the image.
    MACHINE_TYPE_GLOB
    Specifies the pattern that is used to detect deprecated machine types that need to be upgraded. Replace the MACHINE_TYPE_GLOB value with your own pattern.
    RESTART_REQUIRED
    Specifies whether VMs should be restarted after the machine type is updated. If the RESTART_REQUIRED environment variable is set to true, VMs are restarted after the machine type is updated. If you do not want VMs to be restarted, set this value to false.
    NAMESPACE
    Specifies the namespace to look for VMs in. Leave the parameter empty for the job to go over all namespaces in the cluster.
    LABEL_SELECTOR
    Specifies which VMs receive the job action. If you want the job to go over all VMs in the cluster, do not assign a value to the parameter.

Performing bulk actions on virtual machines​

You can perform bulk actions on multiple virtual machines (VMs) simultaneously by using the VirtualMachines list view in the web console. This allows you to efficiently manage a group of VMs with minimal manual effort.

Available bulk actions:

  • Label VMs - Add, edit, or remove labels that are applied across selected VMs.
  • Delete VMs - Select multiple VMs to delete. The confirmation dialog displays the number of VMs selected for deletion.
  • Move VMs to folder - Move selected VMs to a folder. All VMs must belong to the same namespace.
  • LiveMigration - Perform live migration of multiple selected VMs. The confirmation dialog displays the number of VMs selected for migration. The target node is chosen automatically; there is no option of specifying it.
  • Take snapshot - Take snapshots of multiple VMs. The Take snapshots dialog allows you to enter a suffix for the names of the resulting snapshots.

Configuring multiple I/O threads for fast storage access​

You can improve storage performance by configuring multiple I/O threads for a virtual machine (VM) that uses fast storage, such as solid-state drive (SSD) or non-volatile memory express (NVMe). This configuration option is only available by editing YAML of the VM.

note

Multiple I/O threads are supported only when blockMultiQueue is enabled and the disk bus is set to virtio. You must set this configuration for the configuration to work correctly.

Procedure

  1. Click Virtualization → VirtualMachines from the side menu.

  2. Select a virtual machine to open the VirtualMachine details page.

  3. Click the YAML tab to open the VM manifest.

  4. In the YAML editor, locate the spec.template.spec.domain section and add or modify the following fields:

    domain:
      ioThreadsPolicy: supplementalPool
      ioThreads:
        supplementalPoolThreadCount: 4
      devices:
        blockMultiQueue: true
        disks:
        - name: datavolume
          disk:
            bus: virtio
    # ...

  5. Click Save.

    warning

    The spec.template.spec.domain setting cannot be changed while the VM is running. You must stop the VM before applying the changes, and then restart the VM for the new settings to take effect.

Additional resources