title	excerpt	updated
How to start a Public Cloud instance on a bootable volume	Find out how to start an instance on a bootable volume	2025-02-26

Objective

Public Cloud instances come with an original disk that is copied from a system image (Debian 12, Windows Server, etc.). It is also possible to use additional volumes, these are persistent disks that will allow data to be stored.

You can also deploy an operating system to and from a volume. The Public Cloud instance will then start on this volume instead of the original disk.

This guide provides you with instructions on how to start an instance on an attached volume.

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[!success]

OpenStack natively allows you to boot from a volume. It involves making the volume bootable and starting the instance from this volume. The changes will cause the original disk to disappear as the new volume is taking over. The functionality described in this guide eliminates the need to access the original disk and therefore takes advantage of the volume.

Warning

With the current version of OpenStack, rescue-pro mode is not available on an instance booted via a bootable volume.

Requirements

Access to the Horizon interface
Setting OpenStack environment variables

Instructions

Creating a bootable volume from an image.

[!tabs] Horizon

Log in to the Horizon interface.

Select the appropriate region from the drop down menu at the top left.

On the Project tab, open the Volumes{.action} tab and click the Volumes{.action} category.

Click on Create Volume{.action}.

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In the dialog box that opens, enter or select the following values:

Information Description

Volume Name Specify a name for the volume

Description Optional, provide a brief description for the volume

Volume Source Choose the option Image.

{.thumbnail}

Use image as a source You can select the image from the list.

{.thumbnail}

Type Depends on the volume type you want to use

Size (GB) The size of the volume in gibibytes (GiB)

Availability Zone nova

{.thumbnail}

Click on Create Volume{.action}.

The volume will be in a creating state then a downloading state before being available.

{.thumbnail width="800"}

As you can see on the image below or if you click the volume name, it is set as bootable.

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OpenStack client
You can create a bootable volume from an existing image, volume, or volume snapshot. This procedure shows you how to create a volume from an image and use the volume to boot an instance.
$ openstack image list
[!primary]

Note the ID or the name of the image that you wish to use.

Create a bootable 10GB high-speed volume named volume_ubuntu from an Ubuntu 24.04 image:

You can install an image on a volume using the --image argument:
$ openstack volume create --type high-speed --image 2c2e28dc-9124-49c3-b92d-7f00bd83ac86 --size 10 volume_ubuntu
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | nova |
| bootable | false |
| consistencygroup_id | None |
| created_at | 2025-02-06T17:04:34.000000 |
| description | None |
| encrypted | False |
| id | d7611318-fd7b-4b6a-8a7a-8d368049f747 |
| multiattach | False |
| name | volume_ubuntu |
| properties | |
| replication_status | None |
| size | 20 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| type | high-speed |
| updated_at | None |
| user_id | 1a67934f87ef481d9cb617a913bfa8bb |
+---------------------+--------------------------------------+
In this command, 2c2e28dc-9124-49c3-b92d-7f00bd83ac86 is the Ubuntu 24.04 image ID.

[!primary]

Cinder makes a volume bootable when the --image parameter is passed.

Starting an instance using a bootable volume

[!tabs] Horizon

Log in to the Horizon interface.

Select the appropriate region from the drop down menu at the top left.

On the Project tab, open the Compute{.action} tab and click Instances{.action} category.

Click on Launch Instance{.action}.

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In the Launch Instance dialog box, enter the information requested. Refer to the guide Create an instance from the Horizon interface for more details.

In the Source tab, choose "Volume" in the Select Boot Source field.

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A new field for volume selection appears. You can select the previously created volume from the list.

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Click on Launch Instance{.action}.

The instance will be in a build state then Block Device Mapping state before being available.

The instance will eventually have the volume attached.

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OpenStack client

Create an instance, specifying the bootable volume volume_ubuntu as the boot device.

openstack server create --volume volume_ubuntu --flavor d2-2 --key-name publickey --nic net-id=Ext-Net InstanceTest

List the volumes to ensure the status has changed to in-use and the volume is correctly reporting the attachment:

$ openstack volume list
+--------------------------------------+---------------+--------+------+--------------------------------------+
| ID | Name | Status | Size | Attached to |
+--------------------------------------+---------------+--------+------+--------------------------------------+
| d7611318-fd7b-4b6a-8a7a-8d368049f747 | volume_ubuntu | in-use | 10 | Attached to InstanceTest on /dev/sda |
+--------------------------------------+---------------+--------+------+--------------------------------------+

List the volumes attached to the InstanceTest Instance:

$ openstack server volume list InstanceTest
+--------------------------------------+----------+--------------------------------------+--------------------------------------+------+
| ID | Device | Server ID | Volume ID | Tag |
+--------------------------------------+----------+--------------------------------------+--------------------------------------+------+
| d7611318-fd7b-4b6a-8a7a-8d368049f747 | /dev/sda | 5d97c190-f2e3-4af4-a010-6fa7bffbf88b | d7611318-fd7b-4b6a-8a7a-8d368049f747 | None |
+--------------------------------------+----------+--------------------------------------+--------------------------------------+------+

[!primary]

You can also create an instance, using the chosen image and requesting "boot from volume" behavior.

$ openstack server create --flavor d2-2 --key-name publickey --nic net-id=Ext-Net --image b680f0aa-8eb8-4ac8-b008-2a90bb71af4f --boot-from-volume 10 InstanceTest2
+-----------------------------+---------------------------------------------+
| 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 | dP4e4iY3eWWC |
| config_drive | |
| created | 2025-02-06T17:20:06Z |
| flavor | d2-2 (dc3fe9e7-e374-4ad8-b200-fa3bdf45069f) |
| hostId | |
| id | a4632249-e1b4-4047-be1c-87f8b0328f7c |
| image | N/A (booted from volume) |
| key_name | publickey |
| name | InstanceTest2 |
| progress | 0 |
| project_id | d7fb756ae2c24b1cb8630ec7f56ee4a8 |
| properties | |
| security_groups | name='default' |
| status | BUILD |
| updated | 2025-02-06T17:20:06Z |
| user_id | 1a67934f87ef481d9cb617a913bfa8bb |
| volumes_attached | |
+-----------------------------+---------------------------------------------+

In the command above, b680f0aa-8eb8-4ac8-b008-2a90bb71af4f is the Debian 12 image ID.

List the volumes:

List the volumes to ensure the status has changed to in-use and the volume is correctly reporting the attachment.

$ openstack volume list
+--------------------------------------+---------------+--------+------+----------------------------------------+
| ID | Name | Status | Size | Attached to |
+--------------------------------------+---------------+--------+------+----------------------------------------+
| 27f8332d-8bfd-4515-b0a8-18667ae50ff8 | | in-use | 10 | Attached to InstanceTest2 on /dev/sda |
| d7611318-fd7b-4b6a-8a7a-8d368049f747 | volume_ubuntu | in-use | 10 | Attached to InstanceTest on /dev/sda |
+--------------------------------------+---------------+--------+------+----------------------------------------+

List the volume on the server to make sure it's properly attached.

$ openstack server volume list InstanceTest2
+--------------------------------------+----------+--------------------------------------+--------------------------------------+------+
| ID | Device | Server ID | Volume ID | Tag |
+--------------------------------------+----------+--------------------------------------+--------------------------------------+------+
| d7611318-fd7b-4b6a-8a7a-8d368049f747 | /dev/sda | 5d97c190-f2e3-4af4-a010-6fa7bffbf88b | d7611318-fd7b-4b6a-8a7a-8d368049f747 | None |
+--------------------------------------+----------+--------------------------------------+--------------------------------------+------+

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guide.en-gb.md

guide.en-gb.md

Objective

Requirements

Instructions

Creating a bootable volume from an image.

Starting an instance using a bootable volume

Go further

Information	Description
Volume Name	Specify a name for the volume
Description	Optional, provide a brief description for the volume
Volume Source	Choose the option `Image`. {.thumbnail}
Use image as a source	You can select the image from the list. {.thumbnail}
Type	Depends on the volume type you want to use
Size (GB)	The size of the volume in gibibytes (GiB)
Availability Zone	nova {.thumbnail}

Files

guide.en-gb.md

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guide.en-gb.md

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Objective

Requirements

Instructions

Creating a bootable volume from an image.

Starting an instance using a bootable volume

Go further