On 5/16/19 10:20 AM, Thomas Stein wrote: > Hello all. > > My currently used versions: libvirt-5.2.0 and qemu-4.0.0. > > Here is my problem. I'm struggeling since a few weeks with a strange > behaviour by either qemu or libvirt. After a reboot of > the hardware node the $domain.xml contains suddenly a backingStore > setting which was not there before reboot. > Something like that: > >   <devices> >     <emulator>/usr/bin/qemu-system-x86_64</emulator> >     <disk type='file' device='disk'> >       <driver name='qemu' type='qcow2'/> >       <source > file='/var/lib/libvirt/shinymail/shinymail_weekly.qcow2-2019-05-15'/> >       <backingStore type='file'> >         <format type='qcow2'/> >         <source file='/var/lib/libvirt/images/shinymail.qcow2'/> Yes, this matches: >       </backingStore> >       <target dev='vda' bus='virtio'/> >       <address type='pci' domain='0x0000' bus='0x00' slot='0x07' > function='0x0'/> >     </disk> > ... > > This obviousely happens after a backup has been running. The Backup > Script looks like this: > > <snip> > virsh snapshot-create-as --domain shinymail weekly --diskspec > vda,file=/var/lib/libvirt/shinymail/shinymail_weekly.qcow2-$(date > +%Y-%m-%d) --disk-only --atomic --no-metadata the effects of this command. Ultimately, I'm TRYING to get my new 'virsh domain-backup' command integrated into the next libvirt release, which has the advantage of performing a backup WITHOUT having to modify the <domain> XML. But until that happens, any time you use 'virsh snapshot-create-as' as part of a sequence for performing backups, you ARE modifying the <domain> XML, and if you want to revert to the external backup, or if...

> > cp ... > > virsh blockcommit shinymail vda --active --verbose --pivot > <snip> ...blockcommit fails for whatever reason to undo the effects of 'snapshot-create-as' in creating a temporary overlay, then yes, you do have to worry about the temporary overlay being in the way, where you'll have to manually edit the <domain> definition to match the actual disk layouts you really want.

> > So after that "dmblklist shinymail" does show the right source file > but > after a reboot it tries to use the weekly snapshot > again which leads to filesystem errors. > > Someone has an idea what could cause such a behaviour? >