Comment # 2 on bug 1193762 from Steffen Winterfeldt

Yes; vg_b is a VG over sdc & sdd; lvs are created with "lvcreate --type raid1
-m 1 ..." some thin, some normal; then a snapshot of a thin volume and a
snapshot of that snapshot are added.

It's weird, but the PR was about showing nested LVM stuff.