On Tue, Nov 07, 2023 at 05:32:22PM +0800, Han Han wrote: > >>> Before blockcopy, check source image:🔄 ❓ > >>> > >> # qemu-img info -U > >>> /var/lib/avocado/data/avocado-vt/images/jeos-27-x86_64.qcow2🔄 ❓ > >>> > >> > > Was this a compressed qcow2 image when you started? maybe you started with > > an appliance image? > > > Hi, Nir, I have a question here: How to check if a qcow2 image is > compressed?
$ qemu-img map /path/to/image.qcow2 If it says "File contains external, encrypted or compressed clusters" and the image is not encrypted then that's probably it. > The qcow2 file /var/lib/avocado/data/avocado-vt/images/copy.qcow2 is > created without compress options, while the qemu-img info for it > shows `compression type: zlib`. Is that mean the image is compressed > as well? No, in qcow2 there is actually no such thing as a compressed image as opposed to an uncompressed image. qcow2 images contain a collection of data clusters, and each individual cluster can be either compressed or uncompressed. That zlib that qemu-img reports is the algorithm that is used for compressed clusters *IF* they exist, but it's perfectly possible that an image does not have any compressed cluster. Berto
