Openstack - Nova Evacuate without Shared Storage

## What's this?

Nova instance が稼働している compute node が障害停止した際に、Nova instance を別の compute node 上に復旧(=退避)

* Shared storage 無しの場合、全く新しい Nova instance が別の compute node 上で起動される
* ただし、障害停止した compute node 上で稼働していた Nova instance の Parameter (id, hostname, uid, ip ...etc)が使用される
* データは引き継がれない


[条件]

* Shared storage なし
* Nova instance の全データは compute node の local disk にある
* 追加 Volume としての Cinder 未使用
* Hypervisor は KVM

## Initial state

#### Compute node

    # nova service-list | egrep "Host|nova-compute"
    | Binary           | Host    | Zone     | Status  | State | Updated_at                 | Disabled Reason |
    | nova-compute     | node-27 | nova     | enabled | up    | 2015-03-17T08:36:27.000000 | -               |
    | nova-compute     | node-28 | nova     | enabled | up    | 2015-03-17T08:36:24.000000 | -               |
    | nova-compute     | node-31 | nova2    | enabled | up    | 2015-03-17T08:36:24.000000 | -               |

#### AZ

    # nova availability-zone-list | egrep -A 10 "^\| nova"
    | nova                     | available                              |
    | |- node-27               |                                        |
    | | |- nova-compute        | enabled :-) 2015-03-17T08:36:37.000000 |
    | |- node-28               |                                        |
    | | |- nova-compute        | enabled :-) 2015-03-17T08:36:34.000000 |
    | nova2                    | available                              |
    | |- node-31               |                                        |
    | | |- nova-compute        | enabled :-) 2015-03-17T08:36:34.000000 |
    +--------------------------+----------------------------------------+

#### Nova instance is running on node-27

    [root@node-17 ~]# nova list --field name,status,OS-EXT-STS:vm_state,OS-EXT-AZ:availability_zone,OS-EXT-SRV-ATTR:hypervisor_hostname
    +--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+
    | ID                                   | Name       | Status | OS-EXT-STS: Vm State | OS-EXT-AZ: Availability Zone | OS-EXT-SRV-ATTR: Hypervisor Hostname |
    +--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+
    | b103274a-fd6d-42cc-8cfb-c78f3d37c898 | admin_vm01 | ACTIVE | active               | nova                         | node-27                |
    +--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+


## Stop nova-compute service of node-27

#### Stop nova-compute service

    # service openstack-nova-compute stop
    Stopping openstack-nova-compute:                           [  OK  ]

    # service openstack-nova-compute status
    openstack-nova-compute is stopped

    # nova service-list | egrep "Host|nova-compute"
    | Binary           | Host    | Zone     | Status  | State | Updated_at                 | Disabled Reason |
    | nova-compute     | node-27 | nova     | enabled | down  | 2015-03-17T08:38:17.000000 | -               |
    | nova-compute     | node-28 | nova     | enabled | up    | 2015-03-17T08:37:14.000000 | -               |
    | nova-compute     | node-31 | nova2    | enabled | up    | 2015-03-17T08:38:14.000000 | -               |

#### AZ

    # nova availability-zone-list | egrep -A 10 "^\| nova"
    | nova                     | available                              |
    | |- node-27               |                                        |
    | | |- nova-compute        | enabled XXX 2015-03-17T08:38:17.000000 |
    | |- node-28               |                                        |
    | | |- nova-compute        | enabled :-) 2015-03-17T08:37:14.000000 |
    | nova2                    | available                              |
    | |- node-31               |                                        |
    | | |- nova-compute        | enabled :-) 2015-03-17T08:38:14.000000 |
    +--------------------------+----------------------------------------+

## Evacuate

#### Execute evacuate

Evacuate Nova instance to node-28

    # nova evacuate b103274a-fd6d-42cc-8cfb-c78f3d37c898 node-28
    +-----------+--------------+
    | Property  | Value        |
    +-----------+--------------+
    | adminPass | EtDTWFzQAe8q |
    +-----------+--------------+

#### Check the evacuate result

* Nova instance has same parameters (id, hostname, uid, ip ...etc) which previous Nova instance had.
* You can login to this instance by using above adminPass.

````
# nova list --field name,status,,OS-EXT-STS:vm_state,OS-EXT-AZ:availability_zone,OS-EXT-SRV-ATTR:hypervisor_hostname
+--------------------------------------+------------+--------+--+----------------------+------------------------------+--------------------------------------+
| ID                                   | Name       | Status |  | OS-EXT-STS: Vm State | OS-EXT-AZ: Availability Zone | OS-EXT-SRV-ATTR: Hypervisor Hostname |
+--------------------------------------+------------+--------+--+----------------------+------------------------------+--------------------------------------+
| b103274a-fd6d-42cc-8cfb-c78f3d37c898 | admin_vm01 | ACTIVE |  | active               | nova                         | node-28                              |
+--------------------------------------+------------+--------+--+----------------------+------------------------------+--------------------------------------+
````

## Environment

* Openstack : Juno
* Ceph : Firefly

## Reference

[Openstack - Nova Evacuate with Shared Storage][link-01]
[Openstack - Nova Evacuate with Shared Storage with Cinder][link-02]
[Openstack - Nova Evacuate with Shared Storage with Cinder between AZ][link-03]
[Openstack - Nova Evacuate without Shared Storage][link-04]
[Openstack - Nova Host-Evacuate with Shared Storage][link-05]
[Openstack - Nova Host-Evacuate with Shared Storage between AZ][link-06]

[link-01]:http://qiita.com/idzzy/items/3f398ff8eaa3b786fc89
[link-02]:http://qiita.com/idzzy/items/2f1add9d1a03e1a4fdea
[link-03]:http://qiita.com/idzzy/items/8dd2b417f8c5f8efa7c9
[link-04]:http://qiita.com/idzzy/items/860cb6c60ab7433eb817
[link-05]:http://qiita.com/idzzy/items/9f057becb592c4c89137
[link-06]:http://qiita.com/idzzy/items/71287b09de1370c68118