That seems to work now,  although it threw an rpc message error:


cinder migrate 68e364bb-c767-41cf-83b5-6ad5d1a773b4 "cinder01_cinder_volumes_container-b9c480ca@lvm#LVM_iSCSI"


cinder status : 
compute02:~# cinder list |grep 50gtake3
| 40e20ced-fc9e-46a1-ab0c-99add0b6550b | attaching |   50gtake3   |  50  |     None    |  false   |                                      |
| 68e364bb-c767-41cf-83b5-6ad5d1a773b4 |   in-use  |   50gtake3   |  50  |     None    |  false   | fc4d8d0f-3a7c-465a-8abf-18ad7d58139e |

compute02:~# cinder show 68e364bb-c767-41cf-83b5-6ad5d1a773b4 |grep -i mig
|     os-vol-mig-status-attr:migstat    |                            completing                           |
|     os-vol-mig-status-attr:name_id    |                               None                              |

libvirt domain config:
<disk type='block' device='disk'>
 <source dev='/dev/disk/by-path/ip-172.29.239.19:3260-iscsi-iqn.2010-10.org.openstack:volume-68e364bb-c767-41cf-83b5-6ad5d1a773b4-lun-1'/>
 <mirror file='/dev/disk/by-path/ip-172.29.238.110:3260-iscsi-iqn.2010-10.org.openstack:volume-40e20ced-fc9e-46a1-ab0c-99add0b6550b-lun-1' format='raw'/>
 <alias name='virtio-disk2'/>
</disk>

compute02:~# ll /dev/disk/by-path/ip-172.29.238.110:3260-iscsi-iqn.2010-10.org.openstack:volume-40e20ced-fc9e-46a1-ab0c-99add0b6550b-lun-1
lrwxrwxrwx 1 root root 9 Jun  9 17:01 /dev/disk/by-path/ip-172.29.238.110:3260-iscsi-iqn.2010-10.org.openstack:volume-40e20ced-fc9e-46a1-ab0c-99add0b6550b-lun-1 -> ../../sdd

compute02:~# iostat -xm 2 sdd
Linux 3.13.0-48-generic (compute02) 	06/09/2015 	_x86_64_	(24 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.08    0.00    1.07    3.41    0.00   95.43

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sdd               0.00     0.00    0.00  337.50     0.00   160.50   973.94     6.52   19.02    0.00   19.02   1.30  43.80

The migration finished although it threw an rpc message error:

2015-06-09 17:09:24.282 47230 ERROR oslo_messaging.rpc.dispatcher [req-2df6b831-f299-4c32-b8aa-950eb7f693a7 cd93ded7844d44cc9da5f67104813993 fd2714bd133c4ca7b7d09db35735adb2 -
 - -] Exception during message handling: Internal Server Error (HTTP 500) (Request-ID: req-31f70227-f8c4-4a6c-bff6-db541f0ac6c0)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher Traceback (most recent call last):
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 142, in _dispatch_and_
reply
015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     executor_callback))
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 186, in _dispatch
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     executor_callback)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 130, in _do_dispatch
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     result = func(ctxt, **new_args)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 6772, in swap_volume
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     instance)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/exception.py", line 88, in wrapped
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     payload)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 85, in __exit__
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     six.reraise(self.type_, self.value, self.tb)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/exception.py", line 71, in wrapped
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return f(self, context, *args, **kw)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 327, in decorated_function
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     LOG.warning(msg, e, instance_uuid=instance_uuid)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 85, in __exit__
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     six.reraise(self.type_, self.value, self.tb)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 298, in decorated_function
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return function(self, context, *args, **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 355, in decorated_function
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     kwargs['instance'], e, sys.exc_info())
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 85, in __exit__
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     six.reraise(self.type_, self.value, self.tb)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 343, in decorated_function
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return function(self, context, *args, **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 4949, in swap_volume
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     new_volume_id)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 4931, in _swap_volume
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     error=failed)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/nova/volume/cinder.py", line 380, in migrate_volume_completion
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     old_volume_id, new_volume_id, error)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/cinderclient/v1/volumes.py", line 412, in migrate_volume_completion
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     {'new_volume': new_volume_id, 'error': error})[1]
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/cinderclient/v1/volumes.py", line 250, in _action
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return self.api.client.post(url, body=body)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/cinderclient/client.py", line 91, in post
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return self._cs_request(url, 'POST', **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/cinderclient/client.py", line 85, in _cs_request
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return self.request(url, method, **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/cinderclient/client.py", line 80, in request
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     resp = super(LegacyJsonAdapter, self).request(*args, **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/keystoneclient/adapter.py", line 89, in request
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return self.session.request(url, method, **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/keystoneclient/utils.py", line 318, in inner
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     return func(*args, **kwargs)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher   File "/usr/local/lib/python2.7/dist-packages/keystoneclient/session.py", line 389, in request
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher     raise exceptions.from_response(resp, method, url)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher InternalServerError: Internal Server Error (HTTP 500) (Request-ID: req-31f70227-f8c4-4a6c-bff6-db541f0ac6c0)
2015-06-09 17:09:24.282 47230 TRACE oslo_messaging.rpc.dispatcher

Cinder API :

2015-06-09 17:08:56.882 47755 INFO eventlet.wsgi.server [req-4c8a3578-a0d3-4bcb-a6c3-b748e03e0aea cd93ded7844d44cc9da5f67104813993 fd2714bd133c4ca7b7d09db35735adb2 - - -] 172.29.236.15 - - [09/Jun/2015 17:08:56] "GET /v1/fd2714bd133c4ca7b7d09db35735adb2/volumes/68e364bb-c767-41cf-83b5-6ad5d1a773b4 HTTP/1.1" 200 1004 0.166176
2015-06-09 17:08:57.322 47758 INFO cinder.api.v1.volumes [req-6695d74e-db63-44a1-b646-5ef0b11bb291 cc5fbcee81ff4c9eb6663d9977f803a5 fd2714bd133c4ca7b7d09db35735adb2 - - -] vol={'migration_status': u'completing', 'provider_id': None, 'availability_zone': u'nova', 'terminated_at': None, 'updated_at': datetime.datetime(2015, 6, 9, 17, 8, 24), 'provider_geometry': None, 'replication_extended_status': None, 'replication_status': u'disabled', 'snapshot_id': None, 'ec2_id': None, 'deleted_at': None, 'id': u'68e364bb-c767-41cf-83b5-6ad5d1a773b4', 'size': 50L, 'user_id': u'cd93ded7844d44cc9da5f67104813993', 'volume_attachment': [], 'display_description': None, 'volume_admin_metadata': u'[<cinder.db.sqlalchemy.models.VolumeAdminMetadata object at 0x7f3cd38c9710>]', 'project_id': u'fd2714bd133c4ca7b7d09db35735adb2', 'launched_at': datetime.datetime(2015, 6, 1, 19, 5, 47), 'scheduled_at': datetime.datetime(2015, 6, 1, 19, 5, 47), 'status': u'in-use', 'volume_type_id': None, 'multiattach': False, 'deleted': False, 'provider_location': u'172.29.239.19:3260,4 iqn.2010-10.org.openstack:volume-68e364bb-c767-41cf-83b5-6ad5d1a773b4 1', 'host': u'cinder02_cinder_volumes_container-302b93cb@lvm#LVM_iSCSI', 'consistencygroup_id': None, 'source_volid': None, 'provider_auth': u'CHAP xxxx yyy', 'display_name': u'50gtake3', 'bootable': False, 'created_at': datetime.datetime(2015, 6, 1, 19, 5, 47), 'attach_status': u'detached', 'volume_type': None, 'consistencygroup': None, 'volume_metadata': [], '_name_id': None, 'encryption_key_id': None, 'replication_driver_data': None, 'metadata': {u'readonly': u'False'}}
2015-06-09 17:08:57.327 47758 INFO cinder.api.v1.volumes [req-6695d74e-db63-44a1-b646-5ef0b11bb291 cc5fbcee81ff4c9eb6663d9977f803a5 fd2714bd133c4ca7b7d09db35735adb2 - - -] vol={'migration_status': u'target:68e364bb-c767-41cf-83b5-6ad5d1a773b4', 'provider_id': None, 'availability_zone': u'nova', 'terminated_at': None, 'updated_at': datetime.datetime(2015, 6, 9, 17, 1, 26), 'provider_geometry': None, 'replication_extended_status': None, 'replication_status': u'disabled', 'snapshot_id': None, 'ec2_id': None, 'deleted_at': None, 'id': u'40e20ced-fc9e-46a1-ab0c-99add0b6550b', 'size': 50L, 'user_id': u'cd93ded7844d44cc9da5f67104813993', 'volume_attachment': [], 'display_description': None, 'volume_admin_metadata': [], 'project_id': u'fd2714bd133c4ca7b7d09db35735adb2', 'launched_at': datetime.datetime(2015, 6, 9, 17, 1, 24), 'scheduled_at': datetime.datetime(2015, 6, 1, 19, 5, 47), 'status': u'attaching', 'volume_type_id': None, 'multiattach': False, 'deleted': False, 'provider_location': u'172.29.238.110:3260,1 iqn.2010-10.org.openstack:volume-40e20ced-fc9e-46a1-ab0c-99add0b6550b 1', 'host': u'cinder01_cinder_volumes_container-b9c480ca@lvm#LVM_iSCSI', 'consistencygroup_id': None, 'source_volid': None, 'provider_auth': u'CHAP xxxx yyyy', 'display_name': u'50gtake3', 'bootable': False, 'created_at': datetime.datetime(2015, 6, 1, 19, 5, 47), 'attach_status': u'detached', 'volume_type': None, 'consistencygroup': None, 'volume_metadata': [], '_name_id': None, 'encryption_key_id': None, 'replication_driver_data': None}
2015-06-09 17:09:24.180 47756 INFO cinder.api.middleware.fault [req-31f70227-f8c4-4a6c-bff6-db541f0ac6c0 cd93ded7844d44cc9da5f67104813993 fd2714bd133c4ca7b7d09db35735adb2 - - -] http://172.29.236.10:8776/v1/fd2714bd133c4ca7b7d09db35735adb2/volumes/68e364bb-c767-41cf-83b5-6ad5d1a773b4/action returned with HTTP 500
2015-06-09 17:09:24.182 47756 INFO eventlet.wsgi.server [req-31f70227-f8c4-4a6c-bff6-db541f0ac6c0 cd93ded7844d44cc9da5f67104813993 fd2714bd133c4ca7b7d09db35735adb2 - - -] 172.29.236.15 - - [09/Jun/2015 17:09:24] "POST /v1/fd2714bd133c4ca7b7d09db35735adb2/volumes/68e364bb-c767-41cf-83b5-6ad5d1a773b4/action HTTP/1.1" 500 425 60.069031