Brian Moss 1cd948697d Move cli_nova_evacuate.rst out of common/

The Cloud Admin Guide compute-node-down.rst file
has been reworked to link to the User Admin User
Guide rather than include cli_nova_evacuate.rst
directly.

This means that cli_nova_evacuate.rst is no
longer a common file, and it has been moved into
user-guide-admin/source/

Change-Id: Ia4f23bf4aa73d2098863eecb9240182e3939fd87

2015-08-28 16:18:23 +10:00

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Evacuate instances

If a cloud compute node fails due to a hardware malfunction or another reason, you can evacuate instances to make them available again. You can optionally include the target host on the evacuate command. If you omit the host, the scheduler determines the target host.

To preserve user data on server disk, you must configure shared storage on the target host. Also, you must validate that the current VM host is down; otherwise, the evacuation fails with an error.

To list hosts and find a different host for the evacuated instance, run:
```
$ nova host-list
```
Evacuate the instance. You can pass the instance password to the command by using the --password PWD option. If you do not specify a password, one is generated and printed after the command finishes successfully. The following command evacuates a server without shared storage from a host that is down to the specified HOST_B:
```
$ nova evacuate EVACUATED_SERVER_NAME HOST_B
```
The instance is booted from a new disk, but preserves its configuration including its ID, name, uid, IP address, and so on. The command returns a password:
```
+-----------+--------------+
| Property  |    Value     |
+-----------+--------------+
| adminPass | kRAJpErnT4xZ |
+-----------+--------------+
```
To preserve the user disk data on the evacuated server, deploy OpenStack Compute with a shared file system. To configure your system, see Configure migrations in OpenStack Cloud Administrator Guide. In the following example, the password remains unchanged:
```
$ nova evacuate EVACUATED_SERVER_NAME HOST_B --on-shared-storage
```

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Evacuate instances

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