On Thu, Feb 06, 2014 at 12:02:11PM +0530, Kashyap Chamarthy wrote: > On Wed, Feb 05, 2014 at 10:54:15PM +0100, Gergely Horváth wrote: > > Thank you Eric, > > > > On 2014-02-05 17:23, Eric Blake wrote: > > > Yes, live storage migration is possible; although at the moment, qemu is > > > lacking a way to restart the operation if it fails midstream, so libvirt > > > only allows the operation if you are willing to temporarily make your > > > guest transient. > > > > What does this mean? Will I loose anything if - for example - there is > > not enough space on the target device? > > As I understand it, no, you'll not lose anything. > > Here's some old notes for live backup with 'virsh blockcopy', this was > after discussing with Eric > > http://kashyapc.fedorapeople.org/virt/lc-2012/live-backup-with-blockcopy.txt > > Currently due to QEMU's limitation, libvirt expects a domain to be > trasient. Because, blockcopy jobs last forever until canceled, which > implies that they should last across domain restarts if the domain > were persistent. But qemu doesn't yet provide a way to restart a copy > job on domain restart. So the trick is to temporarily make the domain > transient > > > > Or it will still use the original > > disk image? > > > > AFAIK, a transient guest only means it will disappear after the > > virtualisation session ends. > > The disk image stays intact, just it'll disappear from libvirt's view, > hence you take a copy of your XML file below ('virsh dumpxml') does that > > > > > > virsh dumpxml $dom > file > > > virsh undefine $dom > > > virsh blockcopy $dom /ssd/image.raw /hdd/image.raw \ > > > --wait --verbose --pivot > > > virsh define file > > > > I could not find anything about "pivot" or "pivoting"? What does --pivot > > do in this case? > > When you "pivot", libvirt will use the new copy (i.e. /hdd/image.raw > in this case), and this is done while the guest is running. > > Eric, please correct if I said something wrong. Ah, Eric already explained it more eloquently (I hit send before seeing his email). -- /kashyap _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
