Ceph 10.2/Jewel and Xen on Debian Jessie

When using rbd as backend and updating to ceph Jewel, make sure you install qemu-system-x86, qemu-utils and qemu-block-extra from backports (version 2.5), else you might experience virtual machines booting without attached storage.

In the /var/log/xen/qemu-dm-.log zu will find errors like these:

xen be core: xen be: watching backend path (backend/console/3) failed
xen be core: xen be: watching backend path (backend/vkbd/3) failed
xen be core: xen be: watching backend path (backend/vfb/3) failed
xen be core: xen be: watching backend path (backend/qdisk/3) failed
xen be core: xen be: watching backend path (backend/qnic/3) failed