On Thu, Mar 09, 2017 at 11:11:09AM +0100, Piotr Rybicki wrote: > Hello there. > > I discovered, that since qemu 2.8 , external snapshots (very similar to: > http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit),
When I wrote this Wiki page, I tested it only with regular QCOW2 files on EXT4 file system. > freezes block device after: > > # virsh blockcommit (...) > > There is no error message after completion of the command above. > I'm using gluster + ZFS fuse mount as a storage for a VM on gentoo. > libvirt debug showed nothing helpful. > With qemu <2.8 -: snapshots are working as expected. > > Is this a known issue? > Is it qemu or libvirt ? > > If it helps, how can i diagnose this further?a To see what libvirt is sending to QEMU, you can enable the debug log filters, which can give some clue: - In /etc/libvirt/libvirtd.conf, set these config attributes log_filters="1:libvirt 1:qemu 1:conf 1:security 3:event 3:json 3:file 3:object 1:util" log_outputs="1:file:/var/log/libvirt/libvirtd.log" - Restart libvirtd: $ systemctl restart libvirtd - Perform your `blockcommit` test. PS: A gentle reminder -- when reporting upstream, you'll likely better help if you at least test with the latest releases (libvirt-3.1.0, and QEMU 2.8), if not from Git. [...] -- /kashyap