Storage -> New Domain -> iSCSI (or FCP?) -> find and select a LUN that is in use by a VG but not by a domain that exists in the system (and therefore not greyed out) -> "Are you sure?" dialog appears, asking whether to re-use the LUN -> Approve operation and click OK -> nothing happens, new domain is not created and user is returned to the New Domain dialog.
patch merged upstream: http://gerrit.ovirt.org/gitweb?p=ovirt-engine.git;a=commit;h=1ef1c400f32f5eb088e6ee91c28aade9950c3fc7
Verified on RHEVM 3.1 - SI15 RHEVM: rhevm-3.1.0-13.el6ev.noarch VDSM: vdsm-4.9.6-29.0.el6_3.x86_64 LIBVIRT: libvirt-0.9.10-21.el6.x86_64 QEMU & KVM: qemu-kvm-rhev-0.12.1.2-2.298.el6_3.x86_64 SANLOCK: sanlock-2.3-3.el6_3.x86_64