RHEV 3.X - VM migration fails with "could not open disk image", "Permission denied"

Issue

After adding a new Red Hat Enterprise Linux 6.3 host to an existing cluster, Virtual Machines (VMs) that could previously migrate between all hosts in the cluster may fail when attempting to migrate to the new host. The following error messages may be reported in /var/log/vdsm/vdsm.log;

Thread-139631::ERROR::2012-08-06 12:57:59,661::vm::177::vm.Vm::(_recover) vmId=`96d71b75-d878-484f-891c-3e74a1da723b`::internal error process exited while connecting to monitor: qemu-kvm: -drive file=/rhev/data-center/b22e4a3d-41ea-4671-9171-6015ad66ea28/355b6466-1e30-4728-ae75-05d9f82525f5/images/735173ad-9d72-4ec5-8fed-cb3b8ad5195b/4d95edb1-2d04-40bd-89b7-e2720cc7238b,iHost: Red Hat Enterprise Linux (RHEL) 6.2 and laterf=none,id=drive-virtio-disk0,format=raw,serial=c5-8fed-cb3b8ad5195b,cache=none,werror=stop,rerror=stop,aio=native: could not open disk image /rhev/data-center/b22e4a3d-41ea-4671-9171-6015ad66ea28/355b6466-1e30-4728-ae75-05d9f82525f5/images/735173ad-9d72-4ec5-8fed-cb3b8ad5195b/4d95edb1-2d04-40bd-89b7-e2720cc7238b: Permission denied

Thread-139631::ERROR::2012-08-06 12:58:03,435::vm::232::vm.Vm::(run) vmId=`96d71b75-d878-484f-891c-3e74a1da723b`::Traceback (most recent call last):
  File "/usr/share/vdsm/vm.py", line 224, in run
    self._startUnderlyingMigration()
  File "/usr/share/vdsm/libvirtvm.py", line 423, in _startUnderlyingMigration
    libvirt.VIR_MIGRATE_PEER2PEER, None, maxBandwidth)
  File "/usr/share/vdsm/libvirtvm.py", line 445, in f
    ret = attr(*args, **kwargs)
  File "/usr/share/vdsm/libvirtconnection.py", line 63, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 1039, in migrateToURI
    if ret == -1: raise libvirtError ('virDomainMigrateToURI() failed', dom=self)
libvirtError: internal error process exited while connecting to monitor: qemu-kvm: -drive file=/rhev/data-center/b22e4a3d-41ea-4671-9171-6015ad66ea28/355b6466-1e30-4728-ae75-05d9f82525f5/images/735173ad-9d72-4ec5-8fed-cb3b8ad5195b/4d95edb1-2d04-40bd-89b7-e2720cc7238b,if=none,id=drive-virtio-disk0,format=raw,serial=c5-8fed-cb3b8ad5195b,cache=none,werror=stop,rerror=stop,aio=native: could not open disk image /rhev/data-center/b22e4a3d-41ea-4671-9171-6015ad66ea28/355b6466-1e30-4728-ae75-05d9f82525f5/images/735173ad-9d72-4ec5-8fed-cb3b8ad5195b/4d95edb1-2d04-40bd-89b7-e2720cc7238b: Permission denied