Boot from volume
Note
We recommend avoiding using this feature if you can. The boot from volume feature was introduced in OpenStack when virtual machines were by default created on the local disk of the hypervisor. This means that a hypervisor failure could make the virtual machine unavailable. Nowadays on the infomaniak Public Cloud infrastructure, the VM local disk is created on a clustered file system tolerant to hypervisors failure, therefore the boot from volume option doesn't provide advantages anymore.
Warning
If you still want to continue, be aware that several VM operations don't work and will require manual steps such as rescue, rebuild, backup, extend...
Step 1 Create a volume from an image
First of all pick an image
openstack image list
Then create your volume
openstack volume create --size 20 --image ${IMAGE-ID-OR-NAME} my-boot-from-volume-disk
If it works you should see a similar output
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| consistencygroup_id | None |
| created_at | 2021-03-04T12:02:08.000000 |
| description | None |
| encrypted | False |
| id | 61ffca4d-b7d5-4754-ab5c-73f8fc9072f7 |
| multiattach | False |
| name | my-boot-from-volume-disk |
| properties | |
| replication_status | None |
| size | 10 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| type | CEPH_1 |
| updated_at | None |
| user_id | b1580497f51e4d10b9110c60c154562c |
+---------------------+--------------------------------------+
Checking the status again using openstack volume show my-boot-from-volume-disk will allow the volume creation to be followed.
- downloading means that the volume contents is being transferred from the image service to the volume service
- available means the volume can now be used for booting. A set of volume_image meta data is also copied from the image service.
$ openstack volume list
+--------------------------------------+--------------------------+-----------+------+-------------+
| ID | Name | Status | Size | Attached to |
+--------------------------------------+--------------------------+-----------+------+-------------+
| ecfec650-aa3e-45a7-a505-b334cbe60247 | my-boot-from-volume-disk | available | 20 | |
+--------------------------------------+--------------------------+-----------+------+-------------+
Step 2 Create the VM using this volume
$ openstack server create --flavor a4-ram8-disk0 --key-name mykeypair --volume my-boot-from-volume-disk --network ext-net1 my-boot-from-volume-vm
+-----------------------------+------------------------------------------------------+
| Field | Value |
+-----------------------------+------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | |
| OS-EXT-STS:power_state | NOSTATE |
| OS-EXT-STS:task_state | scheduling |
| OS-EXT-STS:vm_state | building |
| OS-SRV-USG:launched_at | None |
| OS-SRV-USG:terminated_at | None |
| accessIPv4 | |
| accessIPv6 | |
| addresses | |
| adminPass | 6fRYwUtmjHUU |
| config_drive | |
| created | 2021-05-28T12:08:58Z |
| flavor | a4-ram8-disk0 (8e5deff9-d4e9-4f6f-952c-10875acecda8) |
| hostId | |
| id | ac81cfb6-651d-4802-bbb7-81567aac5e8a |
| image | N/A (booted from volume) |
| key_name | yubikey-taylor |
| name | my-boot-from-volume-vm |
| progress | 0 |
| project_id | e37a74373c674066bdd68936cb2379a5 |
| properties | |
| security_groups | name='default' |
| status | BUILD |
| updated | 2021-05-28T12:08:58Z |
| user_id | 76e28fda35054408bb3e1ac3c8aed404 |
| volumes_attached | |
+-----------------------------+------------------------------------------------------+
Your VM is ready :
$ openstack server list
+--------------------------------------+------------------------+--------+-----------------------------------------------+---------------------------------+----------------------------+
| ID | Name | Status | Networks | Image | Flavor |
+--------------------------------------+------------------------+--------+-----------------------------------------------+---------------------------------+----------------------------+
| ac81cfb6-651d-4802-bbb7-81567aac5e8a | my-boot-from-volume-vm | ACTIVE | ext-net1=195.15.240.127, 2001:1600:10:100::8f | N/A (booted from volume) | a4-ram8-disk0 |
+--------------------------------------+------------------------+--------+-----------------------------------------------+---------------------------------+----------------------------+
$ openstack server show my-boot-from-volume-vm
+-----------------------------+----------------------------------------------------------+
| Field | Value |
+-----------------------------+----------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | dc3-a-04 |
| OS-EXT-STS:power_state | Running |
| OS-EXT-STS:task_state | None |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2021-05-28T12:09:04.000000 |
| OS-SRV-USG:terminated_at | None |
| accessIPv4 | |
| accessIPv6 | |
| addresses | ext-net1=195.15.240.127, 2001:1600:10:100::8f |
| config_drive | |
| created | 2021-05-28T12:08:58Z |
| flavor | a4-ram8-disk0 (8e5deff9-d4e9-4f6f-952c-10875acecda8) |
| hostId | eb5010c6e36f92f516207aceaff6c1c8144eb8e5b892b1ca5fa6f08b |
| id | ac81cfb6-651d-4802-bbb7-81567aac5e8a |
| image | N/A (booted from volume) |
| key_name | yubikey-taylor |
| name | my-boot-from-volume-vm |
| progress | 0 |
| project_id | e37a74373c674066bdd68936cb2379a5 |
| properties | |
| security_groups | name='default' |
| status | ACTIVE |
| updated | 2021-05-28T12:09:04Z |
| user_id | 76e28fda35054408bb3e1ac3c8aed404 |
| volumes_attached | id='3fbae1c9-0a2e-4e6f-9361-6156b1371189' |
+-----------------------------+----------------------------------------------------------+
Extending/Resizing a boot from volume
If using the OpenStack CLI to extend your volume you might get an error:
openstack volume set --size 100 <VOLUME>
Failed to set volume size: Volume is in in-use state, it must be available before size can be extended
One or more of the set operations failed
This is an openstack client precondition, you can workaround using the Horizon dashboard or using the cinder CLI :
cinder extend <VOLUME> 100
You have to stop / start (reboot is not enough) the VM once the volume has been extended in order to see the new disk size.