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)

Nova instance を停止せずリアルタイムに別の compute node に移動する機能ではない
あくまで shared storage 上のデータを使用して、別の compute node で起動し直す機能

[Case]

Nova instance data is stored in Nova volume of shared storage. Cinder volume is attached to Nova instance.
Nova instance data is stored in Cinder volume (= boot from Cinder volume), Cinder data is stored in Cinder volume of shared storage. Cinder volume is attached to Nova instance.

[条件]

Shared storage あり
Nova instance の全データは Shared storage にある
Cinder volume が Nova instance に接続されている
Hypervisor は KVM

[Case1] Nova instance data is stored in Nova volume of shared storage. Cinder volume is attached to Nova instance.

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    | 2015-03-27T05:41:26.000000 | -               |
| nova-compute     | node-28 | nova     | enabled | up    | 2015-03-27T05:41:32.000000 | -               |
| nova-compute     | node-31 | nova2    | enabled | up    | 2015-03-27T05:41:34.000000 | -               |

AZ

# nova availability-zone-list | egrep -A 10 "^\| nova"
| nova                     | available                              |
| |- node-27               |                                        |
| | |- nova-compute        | enabled :-) 2015-03-27T05:41:36.000000 |
| |- node-28               |                                        |
| | |- nova-compute        | enabled :-) 2015-03-27T05:41:42.000000 |
| nova2                    | available                              |
| |- node-31               |                                        |
| | |- nova-compute        | enabled :-) 2015-03-27T05:41:44.000000 |
+--------------------------+----------------------------------------+

Nova instance is running on node-28

# 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 |
+--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+
| 2a227a9c-801f-458b-ae67-29513e87282b | admin_vm01 | ACTIVE | active               | nova                         | node-28                              |
+--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+

Cinder volume is attached

# nova show admin_vm01 | egrep "Property|os-extended-volumes"
| Property                             | Value                                                    |
| os-extended-volumes:volumes_attached | [{"id": "59dda5f6-d8dd-475d-8445-3c23aa16e3b6"}]         |

# cinder list | egrep "ID|59dda5f6-d8dd-475d-8445-3c23aa16e3b6"
|                  ID                  | Status | Display Name | Size | Volume Type | Bootable |             Attached to              |
| 59dda5f6-d8dd-475d-8445-3c23aa16e3b6 | in-use | admin_vol01  |  1   |     None    |  false   | 2a227a9c-801f-458b-ae67-29513e87282b |

Stop nova-compute service of node-28

Stop nova-compute service

# service openstack-nova-compute stop

# nova service-list | egrep "Host|nova-compute"
| Binary           | Host    | Zone     | Status  | State | Updated_at                 | Disabled Reason |
| nova-compute     | node-27 | nova     | enabled | up    | 2015-03-27T05:49:56.000000 | -               |
| nova-compute     | node-28 | nova     | enabled | down  | 2015-03-27T05:48:02.000000 | -               |
| nova-compute     | node-31 | nova2    | enabled | up    | 2015-03-27T05:49:54.000000 | -               |

AZ

# nova availability-zone-list | egrep -A 10 "^\| nova"
| nova                     | available                              |
| |- node-27               |                                        |
| | |- nova-compute        | enabled :-) 2015-03-27T05:50:06.000000 |
| |- node-28               |                                        |
| | |- nova-compute        | enabled XXX 2015-03-27T05:48:02.000000 |
| nova2                    | available                              |
| |- node-31               |                                        |
| | |- nova-compute        | enabled :-) 2015-03-27T05:50:04.000000 |
+--------------------------+----------------------------------------+

Evacuate

Execute evacuate

Evacuate Nova instance from node-28(inactive) to node-27(active)

# nova evacuate --on-shared-storage 2a227a9c-801f-458b-ae67-29513e87282b node-27

Check the evacuate result

Nova instance is running on node-27(active) by using the previous data stored in shared storage

# 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 |
+--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+
| 2a227a9c-801f-458b-ae67-29513e87282b | admin_vm01 | ACTIVE | active               | nova                         | node-27                              |
+--------------------------------------+------------+--------+----------------------+------------------------------+--------------------------------------+

Cinder volume(vdb) is attached even after evacuate

$ ssh cirros@<INSTANCE> lsblk
NAME   MAJ:MIN RM    SIZE RO TYPE MOUNTPOINT
vda    253:0    0      1G  0 disk
`-vda1 253:1    0 1011.9M  0 part /
vdb    253:16   0      1G  0 disk

[Case2] Nova instance data is stored in Cinder volume (= boot from Cinder volume), Cinder data is stored in Cinder volume of shared storage. Cinder volume is attached to Nova instance.