def StartInstance(self, instance, block_devices, startup_paused):
    """Start an instance.

    For the fake hypervisor, it just creates a file in the base dir,
    creating an exception if it already exists. We don't actually
    handle race conditions properly, since these are *FAKE* instances.

    """
    if self._IsAlive(instance.name):
      raise errors.HypervisorError("Failed to start instance %s: %s" %
                                   (instance.name, "already running"))
    try:
      self._MarkUp(instance, self._InstanceStartupMemory(instance))
    except __HOLE__, err:
      raise errors.HypervisorError("Failed to start instance %s: %s" %
                                   (instance.name, err))
dataset/ETHPy150Open ganeti/ganeti/lib/hypervisor/hv_fake.py/FakeHypervisor.StartInstance