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Hot-plugging virtual disks

Hot-plugging virtual disks is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/.

Hot-plug and hot-unplug virtual disks when you want to add or remove them without stopping your virtual machine or virtual machine instance. This capability is helpful when you need to add storage to a running virtual machine without incurring down-time.

When you hot-plug a virtual disk, you attach a virtual disk to a virtual machine instance while the virtual machine is running.

When you hot-unplug a virtual disk, you detach a virtual disk from a virtual machine instance while the virtual machine is running.

Only data volumes and persistent volume claims (PVCs) can be hot-plugged and hot-unplugged. You cannot hot-plug or hot-unplug container disks.

When you attach a hot-plugged virtual disk to a virtual machine, you cannot perform live migration on the virtual machine. If you attempt to perform live migration on a virtual machine with a hot-plugged disk attached, live migration fails.

Hot-plugging a virtual disk using the CLI

Hot-plug virtual disks that you want to attach to a virtual machine instance (VMI) while a virtual machine is running.

Prerequisites

  • You must have a running virtual machine to hot-plug a virtual disk.

  • You must have at least one data volume or persistent volume claim (PVC) available for hot-plugging.

Procedure

  • Hot-plug a virtual disk by running the following command:

    $ virtctl addvolume <virtual-machine|virtual-machine-instance> --volume-name=<datavolume|PVC> \
[--persist] [--serial=<label-name>]

    • Use the optional --persist flag to add the hot-plugged disk to the virtual machine specification as a permanently mounted virtual disk. Stop, restart, or reboot the virtual machine to permanently mount the virtual disk. After specifying the --persist flag, you can no longer hot-plug or hot-unplug the virtual disk. The --persist flag applies to virtual machines, not virtual machine interfaces.

    • The optional --serial flag allows you to add an alphanumeric string label of your choice. This helps you to identify the hot-plugged disk in a guest virtual machine. If you do not specify this option, the label defaults to the name of the hot-plugged data volume or PVC.

Hot-unplugging a virtual disk using the CLI

Hot-unplug virtual disks that you want to detach from a virtual machine instance (VMI) while a virtual machine is running.

Prerequisites

  • Your virtual machine must be running.

  • You must have at least one data volume or persistent volume claim (PVC) available and hot-plugged.

Procedure

  • Hot-unplug a virtual disk by running the following command:

    $ virtctl removevolume <virtual-machine|virtual-machine-instance> --volume-name=<datavolume|PVC>