We have a Windows 7 VM running on Ubuntu KVM. I needed to give the Windows 7 machine more disk space. This turns out to be really easy (when you know how).
Step 1 – Shutdown the VM
virsh shutdown hostname
Step 2 – Increase the qcow2 image
Find the qcow2 file of the VM and take a backup (just in case).
cp hostname.qcow2 hostname.qcow2.backup qemu-img resize hostname.qcow2 +100GB
Step 3 – Start the VM
Now start the VM.
virsh start hostname
Step 4 – Extend the partition in Window
Windows has a really good partition management utility built into it. Search for “disk management”
Then select the partition, right click and choose extend partition. You should then follow the simple steps and you are done.
Let me know if you have any improvements to this.