Re: [Qemu-discuss] Virtual disk size for image and its backing disk

[Fam Zheng]

On Sat, 01/10 01:53, address@hidden wrote:
> Hi,
> 
> I am trying to use a base image.qcow2 file and create many VMs out of it
> using following command.
> 
> qemu-img -f qcow2 -b image.qcow2 vm1.qcow2
> 
> Now image.qcow2 is a 40G disk with 23G worth of data. So its virtual size
> is 40G and actual size is 23G. However, for vm1.qcow2 I am seeing that its
> virtual size is 23G. When I boot using vm1.qcow2, kernel panics saying that
> it can't read super block at some big offset, which I feel is due to this
> virtual size problem as ext3 might be trying to read super block of each
> block group.
> 

Are you using a compiled qemu from git repo or from your distro? What is the
version number?

Could you show the output of "qemu-img info" and "qemu-img map" on both images?

Fam