RHEV : VM with passthrough SCSI Tape devices fails to boot

Issue

• VM unable to start and fails to boot with the below error

Engine.log

2017-01-07 11:51:13,463 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (ForkJoinPool-1-worker-31121) [] Correlation ID: null, Call Stack: null, Custom Event ID: -1, Message: VM redhat_vm_guest1 is down with error. Exit message: XML error: 'bus', 'target', and 'unit' must be specified for scsi hostdev source address.
2017-01-07 11:51:13,464 INFO  [org.ovirt.engine.core.vdsbroker.VmAnalyzer] (ForkJoinPool-1-worker-31121) [] Running on vds during rerun failed vm: '5defc4b5-e8bd-4ec1-a159-28d9e59505cc'
2017-01-07 11:51:13,465 INFO  [org.ovirt.engine.core.vdsbroker.VmAnalyzer] (ForkJoinPool-1-worker-31121) [] VM '27a2c436-8ed7-4588-97be-5e1c1df9e50c(redhat_vm_guest1) is running in db and not running in VDS 'rhev_host1'
2017-01-07 11:51:13,477 ERROR [org.ovirt.engine.core.vdsbroker.VmsMonitoring] (ForkJoinPool-1-worker-31121) [] Rerun VM '27a2c436-8ed7-4588-97be-5e1c1df9e50c'. Called from VDS 'rhev_host1'
2017-01-07 11:51:13,529 WARN  [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (org.ovirt.thread.pool-6-thread-10) [] Correlation ID: 358e067d, Job ID: fe8eecc3-bcdf-429f-bb96-225c5ca82202, Call Stack: null, Custom Event ID: -1, Message: Failed to run VM redhat_vm_guest1 on Host rhev_host1.

vdsm

Thread-4102::ERROR::2016-04-09 02:03:01,722::vm::759::virt.vm::(_startUnderlyingVm) vmId=`a774093d-fb09-4fb7-aff3-989d7c3755c1`::The vm start process failed
Traceback (most recent call last):
  File "/usr/share/vdsm/virt/vm.py", line 703, in _startUnderlyingVm
    self._run()
  File "/usr/share/vdsm/virt/vm.py", line 1941, in _run
    self._connection.createXML(domxml, flags),
  File "/usr/lib/python2.7/site-packages/vdsm/libvirtconnection.py", line 124, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/vdsm/utils.py", line 1313, in wrapper
    return func(inst, *args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/libvirt.py", line 3611, in createXML
    if ret is None:raise libvirtError('virDomainCreateXML() failed', conn=self)
libvirtError: XML error: 'bus', 'target', and 'unit' must be specified for scsi hostdev source address

• Attaching Tape device via Host Devices from the Virtual machine tab in GUI fails with the virtual machine unable to boot .