234 lines
5.1 KiB
ReStructuredText
234 lines
5.1 KiB
ReStructuredText
.. _section_live-migration-usage:
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=================
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Migrate instances
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=================
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This section discusses how to migrate running instances from one
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OpenStack Compute server to another OpenStack Compute server.
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Before starting a migration, review the Configure migrations section.
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:ref:`section_configuring-compute-migrations`.
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.. note::
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Although the :command:`nova` command is called :command:`live-migration`,
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under the default Compute configuration options, the instances
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are suspended before migration. For more information, see
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`Configure migrations
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<http://docs.openstack.org/newton/config-reference/compute/config-options.html>`_.
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in the OpenStack Configuration Reference.
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**Migrating instances**
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#. Check the ID of the instance to be migrated:
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.. code-block:: console
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$ nova list
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.. list-table::
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:header-rows: 1
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:widths: 46 12 13 22
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* - ID
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- Name
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- Status
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- Networks
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* - d1df1b5a-70c4-4fed-98b7-423362f2c47c
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- vm1
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- ACTIVE
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- private=a.b.c.d
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* - d693db9e-a7cf-45ef-a7c9-b3ecb5f22645
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- vm2
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- ACTIVE
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- private=e.f.g.h
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#. Check the information associated with the instance. In this example,
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``vm1`` is running on ``HostB``:
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.. code-block:: console
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$ nova show d1df1b5a-70c4-4fed-98b7-423362f2c47c
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.. list-table::
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:widths: 30 45
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:header-rows: 1
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* - Property
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- Value
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* - ...
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OS-EXT-SRV-ATTR:host
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...
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flavor
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id
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name
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private network
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status
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...
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- ...
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HostB
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...
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m1.tiny
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d1df1b5a-70c4-4fed-98b7-423362f2c47c
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vm1
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a.b.c.d
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ACTIVE
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...
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#. Select the compute node the instance will be migrated to. In this
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example, we will migrate the instance to ``HostC``, because
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``nova-compute`` is running on it:
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.. list-table:: **nova service-list**
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:widths: 20 9 12 11 9 30 24
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:header-rows: 1
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* - Binary
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- Host
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- Zone
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- Status
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- State
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- Updated_at
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- Disabled Reason
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* - nova-consoleauth
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- HostA
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- internal
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- enabled
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- up
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- 2014-03-25T10:33:25.000000
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- -
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* - nova-scheduler
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- HostA
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- internal
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- enabled
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- up
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- 2014-03-25T10:33:25.000000
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- -
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* - nova-conductor
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- HostA
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- internal
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- enabled
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- up
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- 2014-03-25T10:33:27.000000
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- -
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* - nova-compute
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- HostB
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- nova
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- enabled
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- up
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- 2014-03-25T10:33:31.000000
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- -
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* - nova-compute
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- HostC
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- nova
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- enabled
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- up
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- 2014-03-25T10:33:31.000000
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- -
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* - nova-cert
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- HostA
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- internal
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- enabled
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- up
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- 2014-03-25T10:33:31.000000
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- -
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#. Check that ``HostC`` has enough resources for migration:
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.. code-block:: console
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# nova host-describe HostC
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.. list-table::
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:header-rows: 1
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:widths: 14 14 7 15 12
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* - HOST
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- PROJECT
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- cpu
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- memory_mb
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- disk_gb
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* - HostC
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- (total)
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- 16
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- 32232
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- 878
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* - HostC
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- (used_now)
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- 22
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- 21284
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- 442
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* - HostC
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- (used_max)
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- 22
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- 21284
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- 422
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* - HostC
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- p1
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- 22
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- 21284
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- 422
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* - HostC
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- p2
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- 22
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- 21284
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- 422
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- ``cpu``: Number of CPUs
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- ``memory_mb``: Total amount of memory, in MB
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- ``disk_gb``: Total amount of space for NOVA-INST-DIR/instances, in GB
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In this table, the first row shows the total amount of resources
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available on the physical server. The second line shows the currently
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used resources. The third line shows the maximum used resources. The
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fourth line and below shows the resources available for each project.
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#. Migrate the instance using the :command:`nova live-migration` command:
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.. code-block:: console
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$ nova live-migration SERVER HOST_NAME
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In this example, SERVER can be the ID or name of the instance. Another
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example:
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.. code-block:: console
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$ nova live-migration d1df1b5a-70c4-4fed-98b7-423362f2c47c HostC
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Migration of d1df1b5a-70c4-4fed-98b7-423362f2c47c initiated.
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.. warning::
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When using live migration to move workloads between
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Icehouse and Juno compute nodes, it may cause data loss
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because libvirt live migration with shared block storage
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was buggy (potential loss of data) before version 3.32.
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This issue can be solved when we upgrade to RPC API version 4.0.
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#. Check that the instance has been migrated successfully, using
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:command:`nova list`. If the instance is still running on ``HostB``,
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check the log files at ``src/dest`` for ``nova-compute`` and
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``nova-scheduler`` to determine why.
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