nova/doc/source/admin/migrate-instance-with-snapshot.rst
melanie witt db455548a1 Use force=True for os-brick disconnect during delete
The 'force' parameter of os-brick's disconnect_volume() method allows
callers to ignore flushing errors and ensure that devices are being
removed from the host.

We should use force=True when we are going to delete an instance to
avoid leaving leftover devices connected to the compute host which
could then potentially be reused to map to volumes to an instance that
should not have access to those volumes.

We can use force=True even when disconnecting a volume that will not be
deleted on termination because os-brick will always attempt to flush
and disconnect gracefully before forcefully removing devices.

Closes-Bug: #2004555

Change-Id: I3629b84d3255a8fe9d8a7cea8c6131d7c40899e8
2023-05-10 07:09:05 -07:00

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==================================
Use snapshots to migrate instances
==================================
This guide can be used to migrate an instance between different clouds.
To use snapshots to migrate instances from OpenStack projects to clouds,
complete these steps.
In the source project:
#. :ref:`Create_a_snapshot_of_the_instance`
#. :ref:`Download_the_snapshot_as_an_image`
In the destination project:
#. :ref:`Import_the_snapshot_to_the_new_environment`
#. :ref:`Boot_a_new_instance_from_the_snapshot`
.. note::
Some cloud providers allow only administrators to perform this task.
.. _Create_a_snapshot_of_the_instance:
Create a snapshot of the instance
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#. Shut down the source VM before you take the snapshot to ensure that all
data is flushed to disk. If necessary, list the instances to view the
instance name:
.. code-block:: console
$ openstack server list
+--------------------------------------+------------+--------+------------------+--------------------+-------------------------+
| ID | Name | Status | Networks | Image | Flavor |
+--------------------------------------+------------+--------+------------------+--------------------+-------------------------+
| d0d1b7d9-a6a5-41d3-96ab-07975aadd7fb | myInstance | ACTIVE | private=10.0.0.3 | ubuntu-16.04-amd64 | general.micro.tmp.linux |
+--------------------------------------+------------+--------+------------------+--------------------+-------------------------+
#. Use the :command:`openstack server stop` command to shut down the instance:
.. code-block:: console
$ openstack server stop myInstance
#. Use the :command:`openstack server list` command to confirm that the instance shows a
``SHUTOFF`` status:
.. code-block:: console
$ openstack server list
+--------------------------------------+------------+---------+------------------+--------------------+-------------------------+
| ID | Name | Status | Networks | Image | Flavor |
+--------------------------------------+------------+---------+------------------+--------------------+-------------------------+
| d0d1b7d9-a6a5-41d3-96ab-07975aadd7fb | myInstance | SHUTOFF | private=10.0.0.3 | ubuntu-16.04-amd64 | general.micro.tmp.linux |
+--------------------------------------+------------+---------+------------------+--------------------+-------------------------+
#. Use the :command:`openstack server image create` command to take a snapshot:
.. code-block:: console
$ openstack server image create --name myInstanceSnapshot myInstance
If snapshot operations routinely fail because the user token times out
while uploading a large disk image, consider configuring nova to use
:ref:`service user tokens <service_user_token>`.
#. Use the :command:`openstack image list` command to check the status
until the status is ``ACTIVE``:
.. code-block:: console
$ openstack image list
+--------------------------------------+---------------------------+--------+
| ID | Name | Status |
+--------------------------------------+---------------------------+--------+
| ab567a44-b670-4d22-8ead-80050dfcd280 | myInstanceSnapshot | active |
+--------------------------------------+---------------------------+--------+
.. _Download_the_snapshot_as_an_image:
Download the snapshot as an image
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#. Get the image ID:
.. code-block:: console
$ openstack image list
+--------------------------------------+---------------------------+--------+
| ID | Name | Status |
+--------------------------------------+---------------------------+--------+
| ab567a44-b670-4d22-8ead-80050dfcd280 | myInstanceSnapshot | active |
+--------------------------------------+---------------------------+--------+
#. Download the snapshot by using the image ID that was returned in the
previous step:
.. code-block:: console
$ openstack image save --file snapshot.raw ab567a44-b670-4d22-8ead-80050dfcd280
.. note::
The :command:`openstack image save` command requires the image ID and
cannot use the image name.
Check there is sufficient space on the destination file system for
the image file.
#. Make the image available to the new environment, either through HTTP or
direct upload to a machine (``scp``).
.. _Import_the_snapshot_to_the_new_environment:
Import the snapshot to the new environment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the new project or cloud environment, import the snapshot:
.. code-block:: console
$ openstack image create --container-format bare --disk-format qcow2 \
--file snapshot.raw myInstanceSnapshot
.. _Boot_a_new_instance_from_the_snapshot:
Boot a new instance from the snapshot
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the new project or cloud environment, use the snapshot to create the
new instance:
.. code-block:: console
$ openstack server create --flavor m1.tiny --image myInstanceSnapshot myNewInstance