Paravirtualized Block Drivers for Windows

Introduction

In order to improve disk performance, special paravirtualized block drivers can be installed in Windows guests. You have to download and install those drivers in the VM, as Windows does not provide them by default.

Note: Proxmox recommends using SCSI with VirtIO SCSI single as SCSI Controller Type for VM disks, to have the most features and best performance. VirtIO block may get deprecated in the future.

Download

You can download the latest stable Windows VirtIO drivers from: https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/virtio-win.iso Older Windows Versions may sometimes need older VirtIO drivers. See Windows VirtIO Drivers for more info about the change log, guest OS compatibility and other useful VirtIO guest devices.

Upload the ISO through the Proxmox VE WebUI:An existing Windows installation Select a Storage which allows ISO images in the Proxmox VE WebUI and switch to ISO Temples tab where you can use the "Upload" button or the "Download from URL" on the menu bar.

Installation

Setup On Running Windows

To switch an existing Windows installation to use the VirtIO-SCSI drivers and boot from them, it needs to see a disk requiring the driver before. This can be done by adding a small temporary disk.

Installing the drivers and switching the boot disk to VirtIO SCSI right away (without a dummy disk) will result in a blue screen, claiming an "INACCESSIBLE BOOT DEVICE". In such a situation, you can revert your changes to get Windows to boot again.

Setup Steps

• Prerequisite: An installed running Windows OS and the VirtIO driver ISO
• insert the VirtIO ISO into the VMs CDROM Drive.
• add a small disk (1GB) with Bus Type SCSI (with Options -> SCSI Controller Typ: VirtIO) or VirtIO Block to the VM.
• The disk should get hot plugged. If not, you need to reboot the VM.
• Window should detect the new disk.
  • If the drivers are not yet installed, it will be shown as a new unknown device and ask for drivers. If it doesn't, open the Device Manager, there should be an unknown device
  • Right-click this entry and select "Update Driver Software"
  • Select No when the wizard asks you to search for the driver software (online)
  • Select "Install from a list of specific location"
  • Use the Browse button and navigate to the driver CDROM
  • Usually, selecting the CDROM's top directory (e.g. D:) is enough on newer Windows versions.
  • If that doesn't work, select the appropriate folder for your guest version/architecture manually (use vioscsi for SCSI and vioblk for VirtIO)
  • Click Next to begin the installation. You may get a warning about the driver not being signed on older Windows Versions, select "Continue Anyway".
  • Finish the driver installation

Once the drivers are installed, wait until the disk shows up in the "Disk Management" utility.

(Legacy Note: Windows 2000 may report each disk 8 times in disk management, just install and use the first of each 8-tuple. In "My computer" you should see each disk only once.)

Windows now has the VirtIO SCSI/Block driver installed, and we need to re-attach the VM disks as SCSI or VirtIO block.

• Shut down the VM
• Detach and Remove the dummy disk. After the Detach operation, it will show up as unusedX disk. Removing it right away is recommended to remove uncertainties in the next steps.
• Detach the disk you want to use as Virtio SCSI/Block.
• reattach them by double-clicking the unused disk entry (or use the Edit button). Select SCSI for VirtIO SCSI or VirtIO block.
• Important: Adapt the Boot Order under the VM's Option tab. Make sure that the primary boot device is still the old boot disk.
• You can now start the VM again, it should use the new disk controller.
• If the VM does not boot, you can detach and re-attach the disk as IDE or SATA to redo the procedure with the dummy disk. Don't forget to adapt the boot order!

After you are done, you can:

• remove the temporary VirtIO disk if you haven't already done this and don't need it anymore
• remove the ISO mounted as CD device

Note: If you switch multiple disks to VirtIO drivers, you might have to bring them Online in the Disk Management utility on the first boot after the switch by right-clicking on the disk.

Setup During Windows Installation

Download the VirtIO drivers as described above.

Set the drive type to SCSI (preferred) or VirtIO and the Network also to VirtIO for improved performance. Add a second IDE CDROM drive, in the first mount the Windows installer ISO and in the second the VirtIO driver ISO.

Start the VM and the Installation process. When you arrive at the Disk/Partition selection, you won't see a Disk because the driver isn't loaded. Click on the Load Driver button and then Browse. In the file browser, select the second CDROM drive with the VirtIO drivers and navigate to the vioscsi/WINVERSION/amd64 (or x86 if you have a 32 bit system) and click OK. A RedHat driver should show up in the Driver Installer click next to install them. Repeat the process for other VirtIO driver (e.g. network, qxl, ...).

The Disks should now show up, and you can continue with the installation process as usual.

Old VFD Method

Note: This is kept for legacy reasons, newer Windows versions (XP and newer) should use the above menthod.

You can add the block drivers during install by manually adding a virtual floppy drive (vfd) and a second IDE CDROM Drive (for network VirtIO) to the VM for the initial install (thanks to meto & user100 in the forum).

Download the VirtIO drivers as described above, upload VFD (for disks) and the ISO (for network) to PVE.

Use:

qm set <VMID> -args '-fda /where/you/put/the/file/virtio-win-<VERSION>.vfd'

to add the VFD as virtual floppy to the VM.

Now start the VM and open the console. The standard boot sequence for a new KVM seems to be HDD - Floppy - CD, you can change this but it's just as easy to reboot using the Ctrl-Alt-Del button in the console, use F12 to bring up a boot selection window & boot from CD.

Once windows starts to load, press F6 to get it to look for extra drivers to load. It will automatically load the floppy & away you go.

Note that older VirtIO drivers aren't signed by Windows, so you need to tell the system to continue to load the drivers on a warning.

More information on floppy drives can be found here : http://www.linux-kvm.com/content/block-driver-updates-install-drivers-during-windows-installation

And in the forum here : http://forum.proxmox.com/threads/3711-Floppy-support-hack

See also

• Windows VirtIO Drivers
• Paravirtualized Network Drivers for Windows
• Dynamic Memory Management