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2016-08-30 14:20:56 -0600 asked a question Steps of block live migration

I'm trying to figure out something in openstack when block-migrate an instance, what I want to understand is the steps taken in this type of migration, I've read somewhere that KVM migrates the storage while the VM is still running, then after suspending it (downtime), it sends the memory and a small amount of storage (what have been changed during the pre-copy stage). Is this correct?

I'm using Liberty version of Openstack, and the last version of Libvirt/KVM.

Someone please answer me.


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I'm facing the same problem, can anyone please bring some help.


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2016-05-28 14:46:55 -0600 asked a question cinder: 'module' object has no attribute 'PackException'


When I try to install "c-vol" service on one of my compute nodes, the service shows an error and fails to start, I tried so hard to find what is the issue, I checked on internet a lot, but nothing, it could be something that I have to clean up on the server, but I don't know what it is exactly. (I checked the volume groups and nothing is missing).

Thank you,

Waiting for your answers, below you will find my cinder.conf and the logs from c-vol service:


memcache_servers =
signing_dir = /var/cache/cinder
cafile = /opt/stack/data/ca-bundle.pem
auth_uri =
project_domain_id = default
project_name = service
user_domain_id = default
password = system
username = cinder
auth_url =
auth_plugin = password

os_privileged_user_tenant = service
os_privileged_user_password = system
os_privileged_user_name = nova
glance_api_servers =
osapi_volume_workers = 3
logging_exception_prefix = %(color)s%(asctime)s.%(msecs)03d TRACE %(name)s %(instance)s
logging_debug_format_suffix = from (pid=%(process)d) %(funcName)s %(pathname)s:%(lineno)d
logging_default_format_string = %(asctime)s.%(msecs)03d %(color)s%(levelname)s %(name)s [-%(color)s] %(instance)s%(color)s%(message)s
logging_context_format_string = %(asctime)s.%(msecs)03d %(color)s%(levelname)s %(name)s [%(request_id)s %(user_id)s %(project_id)s%(color)s] %(instance)s%(color)s%(message)s
volume_clear = zero
rpc_backend = rabbit
default_volume_type = lvmdriver-1
enabled_backends = lvmdriver-1
os_region_name = RegionOne
enable_v1_api = true
periodic_interval = 60
state_path = /opt/stack/data/cinder
osapi_volume_listen =
osapi_volume_extension = cinder.api.contrib.standard_extensions
rootwrap_config = /etc/cinder/rootwrap.conf
api_paste_config = /etc/cinder/api-paste.ini
iscsi_helper = tgtadm
verbose = True
debug = True
auth_strategy = keystone
nova_catalog_admin_info = compute:nova:adminURL
nova_catalog_info = compute:nova:publicURL

connection = mysql+pymysql://root:system@

lock_path = /opt/stack/data/cinder

lvm_type = default
iscsi_helper = tgtadm
volume_group = stack-volumes-lvmdriver-1
volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver
volume_backend_name = lvmdriver-1

rabbit_userid = stackrabbit
rabbit_password = system
rabbit_hosts =

and here's the logs:

No handlers could be found for logger "oslo_config.cfg"
2016-05-28 15:34:13.062 WARNING oslo_reports.guru_meditation_report [-] Guru mediation now registers SIGUSR1 and SIGUSR2 by default for backward compatibility. SIGUSR1 will no longer be registered in a future release, so please use SIGUSR2 to generate reports.
2016-05-28 15:34:13.063 DEBUG oslo_concurrency.lockutils [-] Acquired semaphore "singleton_lock" from (pid=25002) lock /usr/local/lib/python2.7/dist-packages/oslo_concurrency/
2016-05-28 15:34:13.063 DEBUG oslo_concurrency.lockutils [-] Releasing semaphore "singleton_lock" from (pid=25002) lock /usr/local/lib/python2.7/dist-packages/oslo_concurrency/
2016-05-28 15:34:13.730 ERROR cinder.cmd.volume [-] Volume service ets-blade-19@lvmdriver-1 failed to start.
2016-05-28 15:34:13.730 TRACE cinder.cmd.volume Traceback (most recent call last):
2016-05-28 15:34:13.730 TRACE cinder.cmd.volume   File "/opt/stack/cinder/cinder/cmd/", line 77, in main
2016-05-28 15:34:13.730 TRACE cinder.cmd.volume     binary='cinder-volume')
2016-05-28 15:34:13.730 TRACE cinder.cmd.volume   File "/opt/stack/cinder/cinder/", line 251, in ...
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2016-02-09 15:31:23 -0600 answered a question Cannot block migrate instance with mapped volumes to caller

Anyone has been through this?

2016-02-06 06:34:41 -0600 asked a question Cannot block migrate instance with mapped volumes to caller

Hello, when I try to block migrate an instance attached to a volume, I get this exception and the migration fails:

Returning exception Migration pre-check error: Cannot block migrate instance 5f9f8015-d347-486e-9021-8ba6101bed68 with mapped volumes to caller

The block migration works when the instance is not attached and when it has a shared storage. Have you any idea what the problem is? I already tried to use the option: --block-device-mapping in nova live-migration but it did not resolve the issue.

I use liberty version of openstack.