Hi,
I'm working on storage part of oVirt project [1]. Besides other options, we 
provide iSCSI storage for VMs. We create PV(s) on attached LUN(s), create 
volume group from this PV(s) and then create LVs on this VG as needed (each 
disk on its LV, similar there's dedicated LV for our metadata etc.). VG is 
what we call (block) storage domain. 

When we remove storage domain we deactivate all LVs and remove LVs and VG from 
all hosts. However, when this fails (e.g. storage is for some reason 
unavailable), hosts are left with stale LVs and VG which can cause various 
issues for us. What we are going to do is to remove these stale VG mappings 
using dmsetup remove command (first we try to remove LVs using lvm, but if 
there are still some mappings, we will try to remove it using dmsetup). 

I'd like to head your opinion on this approach. Is it wise to use dmsetup in 
such case? Or is there any better way how to handle such situations or remove 
stale mappings?

Thanks
Vojta

[1] https://www.ovirt.org/