According to logs, the problem first appeared on July 31st, seemingly after a "zypper dup" that should have involved Tumbleweed snapshots # 20150725, 20150727 and 20150728. The only relevant entry I see in the changelogs of those snapshots is in Changes.20150725.txt: ==== yast2-storage ==== Version update (3.1.63 -> 3.1.64) - Added NoCoW subvolume for /var/lib/libvirt/images (Fate#319299) - 3.1.64 Hope this helps.