VM's crash during migration between hypervisors or remain in a "Paused" state after a migration

Issue

• We have a situation where VMs that are being migrated are not starting up on the other hypervisor.

• After migration, some VMs on one hypervisor show as paused.

• After restarting the vdsmd service some VMs showed as paused.

• The VDSM logs on the host (in the case of migration, the destination host) contain the following error;

Thread-73::ERROR::2014-03-21 19:47:30,443::vm::2169::vm.Vm::(_startUnderlyingVm) vmId=`7d214feb-3e76-4c4d-bc10-173577ee5ea4`::The vm start process failed
Traceback (most recent call last):
  File "/usr/share/vdsm/vm.py", line 2147, in _startUnderlyingVm
    self._waitForIncomingMigrationFinish()
  File "/usr/share/vdsm/vm.py", line 3598, in _waitForIncomingMigrationFinish
    self._domDependentInit()
  File "/usr/share/vdsm/vm.py", line 2935, in _domDependentInit
    self._updateAgentChannels()
  File "/usr/share/vdsm/vm.py", line 2921, in _updateAgentChannels
    os.symlink(path, socketPath)
OSError: [Errno 17] File exists