BUGFIX: Sometimes the volume is not available at BDM

2013-05-17 07:07:26 ERROR nova.compute.manager [req-cd46bf7a-d2ab-4fde-ae46-0e9eb39b6726] Build error: ['Traceback (most recent call
File "/usr/lib/python2.6/site-packages/nova/compute/manager.py", line 500, in _run_instance\n    instance)\n', '
File "/usr/lib/python2.6/site-packages/nova/compute/manager.py", line 738, in _prep_block_device\n    return self._setup_block_devic
File "/usr/lib/python2.6/site-packages/nova/compute/manager.py", line 457, in _setup_block_device_mapping\n    self.volume_api.check
File "/usr/lib/python2.6/site-packages/nova/volume/api.py", line 60, in wrapped\n    return func(self, context, target_obj, *args, *
File "/usr/lib/python2.6/site-packages/nova/volume/api.py", line 319, in check_attach\n    raise exception.InvalidVolume(reason=msg)

4x run instance in parallel:
INSTANCE    i-00000fb2    ami-0000000f    xxx.xxx.xxx.xxx    yyy.yyy.yyy.yyy    running        0        m1.medium    2013-05-17T05:0
INSTANCE    i-00000fb1    ami-0000000f    xxx.xxx.xxx.xxx    yyy.yyy.yyy.yyy    running        0        m1.medium    2013-05-17T05:0
INSTANCE    i-00000fb0    ami-0000000f    xxx.xxx.xxx.xxx    yyy.yyy.yyy.yyy    error          0        m1.medium    2013-05-17T05:0
INSTANCE    i-00000fb3    ami-0000000f    xxx.xxx.xxx.xxx    yyy.yyy.yyy.yyy    running        0        m1.medium    2013-05-17T05:0