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

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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.

Seems like a bug right?

Thanks,

Nitin