Checking volume disk differences
It is important to keep the clones as small as possible. Because if the disk volumes of the virtual machines grow you may run out of disk space.
You can check if some files change unnecessarily, they could be from unexpected activity like unattended package upgrades or system logs. To do so create two clones and keep one shut down. Start the second and do some stuff, check the disk volume grow:
Check volume size
qemu-img info /var/lib/libvirt/clone-1-vdb.qcow2 -U
du -hs /var/lib/libvirt/clone-1-vda.qcow2
If you see the volumes don’t grow unnecessarily, you worry no more.
Compare volume changes
If you want to check the differences between two clones you can compare like this:
virt-diff --format=qcow2 -a clone-2-vda.qcow2 -A clone-1-vda.qcow2 -h --times
Temporay disk volumes
If you need temporary space or a place to store files that change and then get removed, use a TMP Ravada disk volume. Add it in the hardware settings for the virtual machine.