Interesting - at first the only related change seems to be in libvirt. Function storageBackendCreateQemuImgOpts of src/storage/storage_util.c. It is in there since [1] which on itself makes sense to me. Also that particular change is in libvirt since v4.3 which means >=Cosmic and we haven't had major bugs in those releases nor in e.g. cloud archive backports of the same due to it.
Looking forther points in virt-manager to [2] but that is from 2013, but looking at recent related code shows [3] which is only in since v2.2.0 and that would match. That is in /usr/share/virt-manager/virtinst/storage.py of binary "virtinst" of src:virt-manager. >From debug we see the config virt-manager defines for that disk: virt-manager 8272] DEBUG (storage:643) Creating storage volume with xml: <volume> <name>ubuntu19.04.qcow2</name> <capacity>16106127360</capacity> <allocation>16106127360</allocation> <target> <format type="qcow2"/> <features> <lazy_refcounts/> </features> </target> </volume> Which matches what libvirt receives: debug : virStorageVolCreateXML:1499 : pool=0x2867ae0, xmlDesc=<volume> <name>ubuntu19.04.qcow2</name> <capacity>16106127360</capacity> <allocation>16106127360</allocation> <target> <format type="qcow2"/> <features> <lazy_refcounts/> </features> </target> </volume> , flags=0x1 [1]: https://libvirt.org/git/?p=libvirt.git;a=commit;h=c9ec7088c7a3f4cd26bb471f1f243931fff6f4f9 [2]: https://github.com/virt-manager/virt-manager/commit/37350859ce6c46a1c7e6562db8e242a97bcf5bb3 [3]: https://github.com/virt-manager/virt-manager/commit/4f66c423f7833e270b61536d53a0772ce1242abc -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1847105 Title: very slow disk creation, snapshotting To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1847105/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs