windows 7 as kvm guest installation with virtio drivers - detected virtio scsi disk shows wrong capacity

Question

I am trying to install windows 7 64bit as a kvm guest. I read here that I should install the virtio scsi driver during installation.

I use virt-install to start my installation from the command line

virt-install --connect qemu:///system \
    --name win7vnc --ram 2048 --vcpus=2 --cpuset=auto \
    --disk path=win7.img,bus=virtio 
    --network=network=default,model=virtio,mac=RANDOM 
    --graphics vnc,port=5900 
    --disk device=cdrom,path=../../isos/virtio-win-0.1-81.iso  
    --disk device=cdrom,path=../../isos/win7_sp1_ult_64bit/Windows\ 7\ SP1\ Ultimate\ \(64\ Bit\).iso 
    --os-type=windows --os-variant=win7 --boot cdrom,hd    

The installation start fine and as expected windows do not detect a hard disk. So I load driver and the disk is indeed detected. The problem is it only has 99MB capacity, while I created the disk to be 100GB with the command

qemu-img create -f qcow2 win7.img 100G

what could be wrong and the capacity is not correct?

EDIT: picture of the problem

Answer 1

in the end, i set disk settings as if I will create a new disk at the time the virt-install command is run, even though I have a disk image ready in advance. so I run:

virt-install --connect qemu:///system \
    --name win7vnc --ram 2048 --vcpus=2 --cpuset=auto \
    --disk path=win7.img,bus=virtio,size=100,format=qcow2 \
    --network=network=default,model=virtio,mac=RANDOM \
    --graphics vnc,port=5900
    --disk device=cdrom,path=../../isos/virtio-win-0.1-81.iso \
    --disk device=cdrom,path=../../isos/win7_sp1_ult_64bit/Windows\ 7\ SP1\ Ultimate\ \(64\ Bit\).iso \
    --os-type=windows --os-variant=win7 --boot cdrom,hd 

Answer 2

i have written a little shell script to automate installation of Windows 7 in KVM that works for Ubuntu Linux 12.04 as host system:

http://torsten-traenkner.de/linux/create_virtual_machine_with_windows_7.sh.tgz

With a little video:

https://www.youtube.com/watch?v=xwHmdAWkbx4

The script creates a sparse file as a raw disk image. This has the advantage that the virtual disk does not use the complete real disk space at once and that you can mount the raw image easily. If the script does not work for your Linux distribution you can look inside the script to see how it's done.

dd if=/dev/zero of="$DISK_IMAGE_NAME" bs=1 count=0 seek="$virtualMachineSizeInGB"G > /dev/null 2>&1

Answer 3

I wrote up my experience here:

http://www.returnbooleantrue.com/2015/04/making-your-windows-kvm-guest-boxes-fly.html

You can certainly add VirtIO after you finish installing windows.