Migrate instances

Procedure 4.6. To migrate instances

1. Look at the running instances, to get the ID of the instance you wish to migrate.

   $ nova list
   +--------------------------------------+------+--------+-----------------+
   |                  ID                  | Name | Status |Networks         |
   +--------------------------------------+------+--------+-----------------+
   | d1df1b5a-70c4-4fed-98b7-423362f2c47c | vm1  | ACTIVE | private=a.b.c.d |
   | d693db9e-a7cf-45ef-a7c9-b3ecb5f22645 | vm2  | ACTIVE | private=e.f.g.h |
   +--------------------------------------+------+--------+-----------------+

2. Look at information associated with that instance. This example uses 'vm1' from above.

   $ nova show d1df1b5a-70c4-4fed-98b7-423362f2c47c
   +-------------------------------------+----------------------------------------------------------+
   |               Property              |                          Value                           |
   +-------------------------------------+----------------------------------------------------------+
   ...
   | OS-EXT-SRV-ATTR:host                | HostB                                                    |
   ...
   | flavor                              | m1.tiny                                                  |
   | id                                  | d1df1b5a-70c4-4fed-98b7-423362f2c47c                     |
   | name                                | vm1                                                      |
   | private network                     | a.b.c.d                                                  |
   | status                              | ACTIVE                                                   |
   ...
   +-------------------------------------+----------------------------------------------------------+

   In this example, vm1 is running on HostB.

3. Select the server to which instances will be migrated:

   # nova service-list
   +------------------+------------+----------+---------+-------+----------------------------+-----------------+
   | Binary           | Host       | Zone     | Status  | State | Updated_at                 | Disabled Reason |
   +------------------+------------+----------+---------+-------+----------------------------+-----------------+
   | nova-consoleauth | HostA      | internal | enabled | up    | 2014-03-25T10:33:25.000000 | -               |
   | nova-scheduler   | HostA      | internal | enabled | up    | 2014-03-25T10:33:25.000000 | -               |
   | nova-conductor   | HostA      | internal | enabled | up    | 2014-03-25T10:33:27.000000 | -               |
   | nova-compute     | HostB      | nova     | enabled | up    | 2014-03-25T10:33:31.000000 | -               |
   | nova-compute     | HostC      | nova     | enabled | up    | 2014-03-25T10:33:31.000000 | -               |
   | nova-cert        | HostA      | internal | enabled | up    | 2014-03-25T10:33:31.000000 | -               |
   +------------------+-----------------------+----------+---------+-------+----------------------------+-----------------+
                       

   In this example, HostC can be picked up because nova-compute is running on it.

4. Ensure that HostC has enough resources for migration.

   # nova host-describe HostC
   +-----------+------------+-----+-----------+---------+
   | HOST      | PROJECT    | cpu | memory_mb | disk_gb |
   +-----------+------------+-----+-----------+---------+
   | HostC     | (total)    | 16   | 32232    | 878     |
   | HostC     | (used_now) | 13   | 21284    | 442     |
   | HostC     | (used_max) | 13   | 21284    | 442     |
   | HostC     | p1         | 13   | 21284    | 442     |
   | HostC     | p2         | 13   | 21284    | 442     |
   +-----------+------------+-----+-----------+---------+
                       

   • cpu:the number of cpu

   • memory_mb:total amount of memory (in MB)

   • disk_gb:total amount of space for NOVA-INST-DIR/instances (in GB)

   • 1st line shows total amount of resources for the physical server.

   • 2nd line shows currently used resources.

   • 3rd line shows maximum used resources.

   • 4th line and under shows the resource for each project.

5. Use the nova live-migration command to migrate the instances:

   $ nova live-migration server host_name 

   Where server can be either the server's ID or name. For example:

   $ nova live-migration d1df1b5a-70c4-4fed-98b7-423362f2c47c HostC
   Migration of d1df1b5a-70c4-4fed-98b7-423362f2c47c initiated.

   Ensure instances are migrated successfully with nova list. If instances are still running on HostB, check log files (src/dest nova-compute and nova-scheduler) to determine why.

   	Note
   	Although the nova command is called live-migration, under the default Compute configuration options the instances are suspended before migration. For more details, see Configure migrations in OpenStack Configuration Reference.