----- Original Message ----- > From: "Eric Blake" <eblake@xxxxxxxxxx> > To: "Andrew Martin" <amartin@xxxxxxxxxxx>, libvirt-users@xxxxxxxxxx > Sent: Tuesday, April 14, 2015 10:26:50 AM > Subject: Re: Update on-disk XML after virsh snapshot-create-as > > On 04/14/2015 09:17 AM, Andrew Martin wrote: > > Hello, > > > > I am using "virsh snapshot-create-as" to create external snapshots of > > running > > VMs using libvirt 1.0.2 on Ubuntu 12.04 and libvirt 1.2.2 on Ubuntu 14.04. > > This > > works well for creating the snapshots, but I notice that the on-disk XML > > file > > in /etc/libvirt/qemu is not updated with the new disk image file after the > > snapshot is created. This appears to be very similar to > > https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1403841, but occurs > > on > > both 12.04 and 14.04 so I am not sure it is the same bug. > > There have been some bug fixes in newer libvirt; for example, commit > 9f97485 (v1.2.12) is relevant. I'm not sure why your vendor is not > backporting these fixes to the build shipped in Ubuntu, but you can > manually run a newer libvirt to work around the problem. I am unaware of a 3rd-party vendor that backports newer releases of libvirt for Ubuntu - is there one you would recommend? Currently, for 14.04 I am using the packages from the Ubuntu repository, and for 12.04 I built newer versions of libvirt myself in this PPA: https://launchpad.net/~xespackages/+archive/ubuntu/virtualization Is there a better way to keep up-to-date with libvirt releases on Ubuntu LTS? > > > > > This presents a problem if the virtual machine host is suddenly powered off > > since a subsequent boot will find the VM using an older image file to boot > > rather than the most recent snapshot. Is it safe for me to use an external > > wrapper script that does the following to ensure the on-disk XML is > > up-to-date: > > virsh snapshot-create-as .... > > virsh dumpxml > /etc/libvirt/qemu/<domain>.xml > > No. That is not safe. > > > > > Is it safe for me to overwrite the contents of > > /etc/libvirt/qemu/<domain>.xml > > manually while the VM is running? > > Not at all. > http://wiki.libvirt.org/page/FAQ#Where_are_VM_config_files_stored.3F_How_do_I_edit_a_VM.27s_XML_config.3F > > Instead, if you are still suffering from a build of libvirt that fails > to update the files in /etc when taking a snapshot, do some other action > that DOES update /etc (such as changing the domain description), or at a > bare minimum use 'virsh define' instead of manually writing into /etc > yourself. > Thanks for this clarification. It looks like the following would update both the running and on-disk configs? virsh desc <domain> --config --live --new-desc "<new description here>" Thanks, Andrew _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
