"Bad volume specification" error reported when attempting to start a VM.

Issue

• We started getting "Bad volume specification" when trying to power up vms.

• The console on one of the hypervisors also had Multipath errors and "blocked FC remote port time out: removing rport" errors.

• The vdsm.log file on this hypervisor contained;

Thread-209589::ERROR::2014-09-10 16:43:27,461::task::850::TaskManager.Task::(_setError) Task=`38ad116b-b5c7-4f11-96b1-412b5606b1c1`::Unexpected error
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/task.py", line 857, in _run
  File "/usr/share/vdsm/logUtils.py", line 41, in wrapper
  File "/usr/share/vdsm/storage/hsm.py", line 3131, in prepareImage
  File "/usr/share/vdsm/storage/image.py", line 374, in prepare
  File "/usr/share/vdsm/storage/blockSD.py", line 1017, in activateVolumes
  File "/usr/share/vdsm/storage/lvm.py", line 1150, in activateLVs
  File "/usr/share/vdsm/storage/lvm.py", line 821, in _setLVAvailability
CannotActivateLogicalVolumes: Cannot activate Logical Volumes: ('General Storage Exception: ("5 [] [\'  device-mapper: create ioctl on b02f3200--7cc5--4209--90e1--f325bb9babb1-0cdefe7f--1873--4f19--a0f8--47454e87649b failed: Device or resource busy\']\\nb02f3200-7cc5-4209-90e1-f325bb9babb1/[\'0cdefe7f-1873-4f19-a0f8-47454e87649b\', \'677c4b35-f739-459e-8d7e-05d65f2b1b29\']",)',)

and;

Thread-209589::ERROR::2014-09-10 16:43:27,490::vm::725::vm.Vm::(_startUnderlyingVm) vmId=`fc267140-6321-40b8-8d74-a4a5d1b20e92`::The vm start process failed
Traceback (most recent call last):
  File "/usr/share/vdsm/vm.py", line 685, in _startUnderlyingVm
  File "/usr/share/vdsm/libvirtvm.py", line 1444, in _run
  File "/usr/share/vdsm/vm.py", line 746, in preparePaths
  File "/usr/share/vdsm/clientIF.py", line 275, in prepareVolumePath
VolumeError: Bad volume specification {'index': 0, 'iface': 'virtio', 'reqsize': '0', 'format': 'cow', 'bootOrder': '1', 'poolID': '5849b030-626e-47cb-ad90-3ce782d831b3', 'volumeID': '677c4b35-f739-459e-8d7e-05d65f2b1b29', 'apparentsize': '1073741824', 'imageID': 'c02247d6-2a1d-4784-8b11-3d3e5e96ced2', 'specParams': {}, 'readonly': 'false', 'domainID': 'b02f3200-7cc5-4209-90e1-f325bb9babb1', 'optional': 'false', 'deviceId': 'c02247d6-2a1d-4784-8b11-3d3e5e96ced2', 'truesize': '1073741824', 'address': {'bus': '0x00', ' slot': '0x06', ' domain': '0x0000', ' type': 'pci', ' function': '0x0'}, 'device': 'disk', 'shared': 'false', 'propagateErrors': 'off', 'type': 'disk'}