Description of problem: Currently, there seems to be no way of changing a disk's interface type. For example, a disk of 'virtio' interface cannot be added to another VM via the 'virtio-SCSI' interface. This is needed in some cases for DR and backup.
Moving from 4.0 alpha to 4.0 beta since 4.0 alpha has been already released and bug is not ON_QA.
Doctext tracked on bug 1139879, setting requires-doctext- for this one.
Executed the feature basic flows after setup upgrade (3.6 -> 4.0): https://polarion.engineering.redhat.com/polarion/#/project/RHEVM3/testrun?id=4_0_Storage_Ability_to_change_disk_interface_for_a_VM_disk_run_31_06_2016 Tested using Webadmin, All passed. Note that for REST API, we're still block due to: Bug 1352657 - GET of diskattachment returns a list of objects without the href property Tested using: rhevm-4.0.0.6-0.1.el7ev.noarch vdsm-4.18.4-2.el7ev.x86_64 libvirt-daemon-1.2.17-13.el7_2.5.x86_64 qemu-kvm-rhev-2.3.0-31.el7_2.18.x86_64