Launch an instance from a volume

You can boot instances from a volume instead of an image.

To complete these tasks, use these parameters on the openstack server create command:

Task

openstack server create parameter

Information

Boot an instance from an image and attach a non-bootable volume.

--block-device

Boot instance from image and attach non-bootable volume

Create a volume from an image and boot an instance from that volume.

--block-device

Create volume from image and boot instance

Boot from an existing source image, volume, or snapshot.

--block-device

Create volume from image and boot instance

Attach a swap disk to an instance.

--swap

Attach swap or ephemeral disk to an instance

Attach an ephemeral disk to an instance.

--ephemeral

Attach swap or ephemeral disk to an instance

Note

To attach a volume to a running instance, refer to the Cinder documentation.

Note

The maximum limit on the number of disk devices allowed to attach to a single server is configurable with the option compute.max_disk_devices_to_attach.

Boot instance from image and attach non-bootable volume

Create a non-bootable volume and attach that volume to an instance that you boot from an image.

To create a non-bootable volume, do not create it from an image. The volume must be entirely empty with no partition table and no file system.

  1. Create a non-bootable volume.

    $ openstack volume create --size 8 my-volume
    +---------------------+--------------------------------------+
    | Field               | Value                                |
    +---------------------+--------------------------------------+
    | attachments         | []                                   |
    | availability_zone   | nova                                 |
    | bootable            | false                                |
    | consistencygroup_id | None                                 |
    | created_at          | 2016-11-25T10:37:08.850997           |
    | description         | None                                 |
    | encrypted           | False                                |
    | id                  | b8f7bbec-6274-4cd7-90e7-60916a5e75d4 |
    | migration_status    | None                                 |
    | multiattach         | False                                |
    | name                | my-volume                            |
    | properties          |                                      |
    | replication_status  | disabled                             |
    | size                | 8                                    |
    | snapshot_id         | None                                 |
    | source_volid        | None                                 |
    | status              | creating                             |
    | type                | None                                 |
    | updated_at          | None                                 |
    | user_id             | 0678735e449149b0a42076e12dd54e28     |
    +---------------------+--------------------------------------+
    
  2. List volumes.

    $ openstack volume list
    +--------------------------------------+--------------+-----------+------+-------------+
    | ID                                   | Name         | Status    | Size | Attached to |
    +--------------------------------------+--------------+-----------+------+-------------+
    | b8f7bbec-6274-4cd7-90e7-60916a5e75d4 | my-volume    | available |    8 |             |
    +--------------------------------------+--------------+-----------+------+-------------+
    
  3. Boot an instance from an image and attach the empty volume to the instance.

    $ openstack server create --flavor 2 --image 98901246-af91-43d8-b5e6-a4506aa8f369 \
      --block-device source=volume,id=d620d971-b160-4c4e-8652-2513d74e2080,dest=volume,shutdown=preserve \
      myInstanceWithVolume
    +--------------------------------------+--------------------------------------------+
    | Field                                | Value                                      |
    +--------------------------------------+--------------------------------------------+
    | OS-DCF:diskConfig                    | MANUAL                                     |
    | OS-EXT-AZ:availability_zone          | nova                                       |
    | OS-EXT-SRV-ATTR:host                 | -                                          |
    | OS-EXT-SRV-ATTR:hypervisor_hostname  | -                                          |
    | OS-EXT-SRV-ATTR:instance_name        | instance-00000004                          |
    | OS-EXT-STS:power_state               | 0                                          |
    | OS-EXT-STS:task_state                | scheduling                                 |
    | OS-EXT-STS:vm_state                  | building                                   |
    | OS-SRV-USG:launched_at               | -                                          |
    | OS-SRV-USG:terminated_at             | -                                          |
    | accessIPv4                           |                                            |
    | accessIPv6                           |                                            |
    | adminPass                            | ZaiYeC8iucgU                               |
    | config_drive                         |                                            |
    | created                              | 2014-05-09T16:34:50Z                       |
    | flavor                               | m1.small (2)                               |
    | hostId                               |                                            |
    | id                                   | 1e1797f3-1662-49ff-ae8c-a77e82ee1571       |
    | image                                | cirros-0.3.5-x86_64-uec (98901246-af91-... |
    | key_name                             | -                                          |
    | metadata                             | {}                                         |
    | name                                 | myInstanceWithVolume                       |
    | os-extended-volumes:volumes_attached | [{"id": "d620d971-b160-4c4e-8652-2513d7... |
    | progress                             | 0                                          |
    | security_groups                      | default                                    |
    | status                               | BUILD                                      |
    | tenant_id                            | ccef9e62b1e645df98728fb2b3076f27           |
    | updated                              | 2014-05-09T16:34:51Z                       |
    | user_id                              | fef060ae7bfd4024b3edb97dff59017a           |
    +--------------------------------------+--------------------------------------------+
    

Create volume from image and boot instance

You can create a volume from an existing image, volume, or snapshot. This procedure shows you how to create a volume from an image, and use the volume to boot an instance.

  1. List the available images.

    $ openstack image list
    +-----------------+---------------------------------+--------+
    | ID              | Name                            | Status |
    +-----------------+---------------------------------+--------+
    | 484e05af-a14... | Fedora-x86_64-20-20131211.1-sda | active |
    | 98901246-af9... | cirros-0.3.5-x86_64-uec         | active |
    | b6e95589-7eb... | cirros-0.3.5-x86_64-uec-kernel  | active |
    | c90893ea-e73... | cirros-0.3.5-x86_64-uec-ramdisk | active |
    +-----------------+---------------------------------+--------+
    

    Note the ID of the image that you want to use to create a volume.

    If you want to create a volume to a specific storage backend, you need to use an image which has cinder_img_volume_type property. In this case, a new volume will be created as storage_backend1 volume type.

    $ openstack image show 98901246-af9d-4b61-bea8-09cc6dc41829
    +------------------+------------------------------------------------------+
    | Field            | Value                                                |
    +------------------+------------------------------------------------------+
    | checksum         | ee1eca47dc88f4879d8a229cc70a07c6                     |
    | container_format | bare                                                 |
    | created_at       | 2016-10-08T14:59:05Z                                 |
    | disk_format      | qcow2                                                |
    | file             | /v2/images/9fef3b2d-c35d-4b61-bea8-09cc6dc41829/file |
    | id               | 98901246-af9d-4b61-bea8-09cc6dc41829                 |
    | min_disk         | 0                                                    |
    | min_ram          | 0                                                    |
    | name             | cirros-0.3.5-x86_64-uec                              |
    | owner            | 8d8ef3cdf2b54c25831cbb409ad9ae86                     |
    | protected        | False                                                |
    | schema           | /v2/schemas/image                                    |
    | size             | 13287936                                             |
    | status           | active                                               |
    | tags             |                                                      |
    | updated_at       | 2016-10-19T09:12:52Z                                 |
    | virtual_size     | None                                                 |
    | visibility       | public                                               |
    +------------------+------------------------------------------------------+
    
  2. List the available flavors.

    $ openstack flavor list
    +-----+-----------+-------+------+-----------+-------+-----------+
    | ID  | Name      |   RAM | Disk | Ephemeral | VCPUs | Is_Public |
    +-----+-----------+-------+------+-----------+-------+-----------+
    | 1   | m1.tiny   |   512 |    1 |         0 |     1 | True      |
    | 2   | m1.small  |  2048 |   20 |         0 |     1 | True      |
    | 3   | m1.medium |  4096 |   40 |         0 |     2 | True      |
    | 4   | m1.large  |  8192 |   80 |         0 |     4 | True      |
    | 5   | m1.xlarge | 16384 |  160 |         0 |     8 | True      |
    +-----+-----------+-------+------+-----------+-------+-----------+
    

    Note the ID of the flavor that you want to use to create a volume.

  3. To create a bootable volume from an image and launch an instance from this volume, use the --block-device parameter with the nova boot command.

    For example:

    $ nova boot --flavor FLAVOR --block-device \
      source=SOURCE,id=ID,dest=DEST,size=SIZE,shutdown=PRESERVE,bootindex=INDEX \
      NAME
    

    The parameters are:

    • --flavor The flavor ID or name.

    • --block-device source=SOURCE,id=ID,dest=DEST,size=SIZE,shutdown=PRESERVE,bootindex=INDEX

      source=SOURCE

      The type of object used to create the block device. Valid values are volume, snapshot, image, and blank.

      id=ID

      The ID of the source object.

      dest=DEST

      The type of the target virtual device. Valid values are volume and local.

      size=SIZE

      The size of the volume that is created.

      shutdown={preserve|remove}

      What to do with the volume when the instance is deleted. preserve does not delete the volume. remove deletes the volume.

      bootindex=INDEX

      Orders the boot disks. Use 0 to boot from this volume.

    • NAME. The name for the server.

    See the nova boot command documentation and Block Device Mapping in Nova for more details on these parameters.

    Note

    As of the Stein release, the openstack server create command does not support creating a volume-backed server from a source image like the nova boot command. The next steps will show how to create a bootable volume from an image and then create a server from that boot volume using the openstack server create command.

  4. Create a bootable volume from an image. Cinder makes a volume bootable when --image parameter is passed.

    $ openstack volume create --image IMAGE_ID --size SIZE_IN_GB bootable_volume
    

    Note

    A bootable encrypted volume can also be created by adding the –type ENCRYPTED_VOLUME_TYPE parameter to the volume create command:

    $ openstack volume create --type ENCRYPTED_VOLUME_TYPE --image IMAGE_ID --size SIZE_IN_GB bootable_volume
    +---------------------+--------------------------------------+
    | Field               | Value                                |
    +---------------------+--------------------------------------+
    | attachments         | []                                   |
    | availability_zone   | nova                                 |
    | bootable            | false                                |
    | consistencygroup_id | None                                 |
    | created_at          | 2017-06-13T18:59:57.626872           |
    | description         | None                                 |
    | encrypted           | True                                 |
    | id                  | ded57a86-5b51-43ab-b70e-9bc0f91ef4ab |
    | multiattach         | False                                |
    | name                | bootable_volume                      |
    | properties          |                                      |
    | replication_status  | None                                 |
    | size                | 1                                    |
    | snapshot_id         | None                                 |
    | source_volid        | None                                 |
    | status              | creating                             |
    | type                | LUKS                                 |
    | updated_at          | None                                 |
    | user_id             | 459ae34ffcd94edab0c128ed616bb19f     |
    +---------------------+--------------------------------------+
    

    This requires an encrypted volume type, which must be created ahead of time by an admin. Refer to horizonadmin/manage-volumes.html#create-an-encrypted-volume-type. in the OpenStack Horizon Administration Guide.

  5. Create a VM from previously created bootable volume. The volume is not deleted when the instance is terminated.

    Note

    The example here uses the --volume option for simplicity. The --block-device option could also be used for more granular control over the parameters. See the openstack server create documentation for details.

    $ openstack server create --flavor 2 --volume VOLUME_ID myInstanceFromVolume
    +--------------------------------------+--------------------------------+
    | Field                                | Value                          |
    +--------------------------------------+--------------------------------+
    | OS-EXT-STS:task_state                | scheduling                     |
    | image                                | Attempt to boot from volume    |
    |                                      | - no image supplied            |
    | OS-EXT-STS:vm_state                  | building                       |
    | OS-EXT-SRV-ATTR:instance_name        | instance-00000003              |
    | OS-SRV-USG:launched_at               | None                           |
    | flavor                               | m1.small                       |
    | id                                   | 2e65c854-dba9-4f68-8f08-fe3... |
    | security_groups                      | [{u'name': u'default'}]        |
    | user_id                              | 352b37f5c89144d4ad053413926... |
    | OS-DCF:diskConfig                    | MANUAL                         |
    | accessIPv4                           |                                |
    | accessIPv6                           |                                |
    | progress                             | 0                              |
    | OS-EXT-STS:power_state               | 0                              |
    | OS-EXT-AZ:availability_zone          | nova                           |
    | config_drive                         |                                |
    | status                               | BUILD                          |
    | updated                              | 2014-02-02T13:29:54Z           |
    | hostId                               |                                |
    | OS-EXT-SRV-ATTR:host                 | None                           |
    | OS-SRV-USG:terminated_at             | None                           |
    | key_name                             | None                           |
    | OS-EXT-SRV-ATTR:hypervisor_hostname  | None                           |
    | name                                 | myInstanceFromVolume           |
    | adminPass                            | TzjqyGsRcJo9                   |
    | tenant_id                            | f7ac731cc11f40efbc03a9f9e1d... |
    | created                              | 2014-02-02T13:29:53Z           |
    | os-extended-volumes:volumes_attached | [{"id": "2fff50ab..."}]        |
    | metadata                             | {}                             |
    +--------------------------------------+--------------------------------+
    
  6. List volumes to see the bootable volume and its attached myInstanceFromVolume instance.

    $ openstack volume list
    +---------------------+-----------------+--------+------+---------------------------------+
    | ID                  | Name            | Status | Size | Attached to                     |
    +---------------------+-----------------+--------+------+---------------------------------+
    | c612f739-8592-44c4- | bootable_volume | in-use |  10  | Attached to myInstanceFromVolume|
    | b7d4-0fee2fe1da0c   |                 |        |      | on /dev/vda                     |
    +---------------------+-----------------+--------+------+---------------------------------+
    

Attach swap or ephemeral disk to an instance

Use the nova boot --swap parameter to attach a swap disk on boot or the nova boot --ephemeral parameter to attach an ephemeral disk on boot. When you terminate the instance, both disks are deleted.

Boot an instance with a 512 MB swap disk and 2 GB ephemeral disk.

$ nova boot --flavor FLAVOR --image IMAGE_ID --swap 512 \
  --ephemeral size=2 NAME

Note

The flavor defines the maximum swap and ephemeral disk size. You cannot exceed these maximum values.