On Sun, Jul 13, 2014 at 4:28 PM, Andrey Korolyov <and...@xdel.ru> wrote: > Hello, > > the issue is not specific to the iothread code because generic > virtio-blk also hangs up: > > Given code set like in the > http://www.mail-archive.com/qemu-devel@nongnu.org/msg246164.html, > launch a VM with virtio-blk disk and writeback rbd backend, fire up > fio, migrate once with libvirt: > > time virsh migrate vm27842 qemu+tcp://10.6.0.10/system --live > --persistent --undefinesource --timeout 60 > > > real 1m2.969s > user 0m0.016s > sys 0m0.008s > > For ones who are unfamiliar with libvirt syntax this means that the > live migration was failed to complete over sixty seconds, VM was > frozen, moved and re-launched at the destination. After this, I/O gets > stuck forever. Any diagnostic information is available upon request if > there will be difficulties repeating the issue.
Small follow-up: issue have probabilistic nature, as it looks - by limited number of runs, it is reproducible within three cases: 1) live migration went well, I/O locked up, 2) live migration failed by timeout, I/O locked up, 3) live migration went well and disk was not locked, but on backward migration we are always hitting 2).
