Windows 7 guest installer does not detect drive if physical partition used instead of disk file.

Windows 7 guest installer does not detect drive if physical partition used instead of disk file.

[Emmanuel Noobadmin]

Running
3.18.9-200.fc21.x86_64
qemu 2:2.1.3-3.fc21
libvirt 1.2.9.2-1.fc21
System is a Thinkpad X250 with Intel i7-5600u Broadwell GT2

I'm trying to replace the Win7 installation on my laptop with Fedora
21 and virtualizing Windows 7 for work purposes. I'd prefer to give
the guest its own NTFS partition instead of using a file for both
performance and ease of potential recovery.

So I've set aside unpartitioned space on the hard disk and added
/dev/sda to the virt-manager storage pool, created a new volume and
assigned it to the guest as an IDE drive. Unfortunately, the Windows 7
installer does not see this drive despite being "IDE" and not virtio.
If I use a qcow2 file as the drive, the installer has no problems
detecting it.

To eliminate virt-manager from the equation, I've also tried to do a
very basic install using virt-install with similar results, the
physical partition cannot be detected regardless of bus type
(IDE/SATA/virtio) even with the signed Redhat virtio drivers loaded by
the installer.

I was unable to find any similar issues or solutions online except a 2
year old thread on linuxquestions which quoted that we must specify
the whole disk instead of a partition. However, I cannot find the
source of that quote.
http://www.linuxquestions.org/questions/linux-virtualization-and-cloud-90/qemu-kvm-on-a-real-partition-947162/

Is this really the case and the reason why Windows 7 cannot see the
physical partition or there is something else I am doing wrong?

Re: Windows 7 guest installer does not detect drive if physical partition used instead of disk file.

[Stefan Hajnoczi]

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On Sat, Mar 21, 2015 at 01:50:46AM +0800, Emmanuel Noobadmin wrote:
> Running
> 3.18.9-200.fc21.x86_64
> qemu 2:2.1.3-3.fc21
> libvirt 1.2.9.2-1.fc21
> System is a Thinkpad X250 with Intel i7-5600u Broadwell GT2
> 
> I'm trying to replace the Win7 installation on my laptop with Fedora
> 21 and virtualizing Windows 7 for work purposes. I'd prefer to give
> the guest its own NTFS partition instead of using a file for both
> performance and ease of potential recovery.
> 
> So I've set aside unpartitioned space on the hard disk and added
> /dev/sda to the virt-manager storage pool, created a new volume and
> assigned it to the guest as an IDE drive. Unfortunately, the Windows 7
> installer does not see this drive despite being "IDE" and not virtio.
> If I use a qcow2 file as the drive, the installer has no problems
> detecting it.
> 
> To eliminate virt-manager from the equation, I've also tried to do a
> very basic install using virt-install with similar results, the
> physical partition cannot be detected regardless of bus type
> (IDE/SATA/virtio) even with the signed Redhat virtio drivers loaded by
> the installer.
> 
> I was unable to find any similar issues or solutions online except a 2
> year old thread on linuxquestions which quoted that we must specify
> the whole disk instead of a partition. However, I cannot find the
> source of that quote.
> http://www.linuxquestions.org/questions/linux-virtualization-and-cloud-90/qemu-kvm-on-a-real-partition-947162/
> 
> Is this really the case and the reason why Windows 7 cannot see the
> physical partition or there is something else I am doing wrong?

I have CCed the libvirt mailing list, since KVM is a component here but
your question seems to be mainly about libvirt, virt-manager,
virt-install, etc.

It sounds like you want an NTFS partition on /dev/sda.  That requires
passing the whole /dev/sda drive to the guest - and the Windows
installer might overwrite your GRUB Master Boot Record.  Be careful when
trying to do this.

Also keep in mind that the virtual machine's hardware and your physical
hardware are probably quiet different (different chipsets, PCI devices,
etc).  Windows might not be happy booting on the physical host if it was
installed under KVM, and vice versa.  This is known as
physical-to-virtual (p2v) migration and means some tweaks or driver
installs may be necessary to make Windows run after switching.

Stefan

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Re: Windows 7 guest installer does not detect drive if physical partition used instead of disk file.

[Emmanuel Noobadmin]

On 3/23/15, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> I have CCed the libvirt mailing list, since KVM is a component here but
> your question seems to be mainly about libvirt, virt-manager,
> virt-install, etc.

Apologies for posting to the wrong list, I assumed it would be KVM
related as the guest could run but could not see the drive.

More information
1. install guest with /dev/sdxx as virtio device (the problem case)
- installer does not see any drive
- load drivers on Redhat virtio "cdrom"
- installer still does not see any drive

2. Install guest with qcow2 disk file as virtio device
- as previous scenario but installer see drives after installing drivers

3. install guest with qcow2 disk file as IDE device
- complete installation
- add /dev/sdxx as virtio disk
- goto Windows Device Manager and update virtio driver for unknown controller
- Windows see /dev/sdxx after driver installed


> It sounds like you want an NTFS partition on /dev/sda.  That requires
> passing the whole /dev/sda drive to the guest - and the Windows
> installer might overwrite your GRUB Master Boot Record.  Be careful when
> trying to do this.

Yes, I wanted to give Windows its own native partition that could be
read directly if I had to yank the disk and put it into a Windows
machine. Is this why #3 works but not #1? That as long as I want to
install Windows directly to an NTFS partition on/dev/sda, it is
required that I pass the whole drive to Windows?