Creating and using volumes

Creating a volume via the dashboard

The easiest method to create and attach a volume to an instance would be to use the Catalyst Cloud web dashboard. From the volumes tab on the dashboard you can create, delete, and manage your block storage volumes.


Once you are here we we navigate to the Create Volume button on the top right. We are then met with this screen.


From this example I have already filled out the requirements to create the instance:

  1. A name

  2. The volume type

  3. The size (in this example 50 GB)

  4. The region

Once we have all of these set, then we are create our volume.


The create volume screen allows you to select a volume source to create your new volume from. We strongly advise against using “snapshot” or “volume” as a source for the new volume. These will create hard dependencies on the volume or snapshot selected, meaning you cannot delete the source volume or snapshot until your new volume and all others created from the same source are deleted.

After we have our new volume, we then are going to attach our volume to an instance. To do this we have to go to the Manage Attachments section.


From this screen we select the instance we want to attach our volume to. The dropdown from this pop up will display all your instances; for this example I am using an instance called “basic-instance”. We also provide the path in the file structure where we want our volume to be available from; in this example I use /dev/vdb.


Once this is done, then you should be able to see your new volume attached to your instance.

Creating a volume using programmatic methods

To create and attach a new volume, you can use one of the methods below:


You must have sourced an openrc file before you can use any of the following methods to create or attach a volume.

The following command will create a volume on your project:

$ openstack volume create --description 'database volume' --size 50 db-vol-01

| Field               | Value                                |
| attachments         | []                                   |
| availability_zone   | nz-por-1a                            |
| bootable            | false                                |
| consistencygroup_id | None                                 |
| created_at          | 2016-08-18T23:08:40.021641           |
| description         | database volume                      |
| encrypted           | False                                |
| id                  | 7e94a2f6-b4d2-47f1-83f7-xxxxxxxxxxxx |
| multiattach         | False                                |
| name                | db-vol-01                            |
| properties          |                                      |
| replication_status  | disabled                             |
| size                | 50                                   |
| snapshot_id         | None                                 |
| source_volid        | None                                 |
| status              | creating                             |
| type                | b1.standard                          |
| updated_at          | None                                 |
| user_id             | 53b94a52e9dcxxxxxxx0079a9a3d6434     |

The next command will attach the previous volume to your instance. This command assumes that your volume name is unique; If you have volumes with duplicate names you will need to use the volume ID to attach the correct volume to your compute instance.
$ openstack server add volume <INSTANCE_NAME> <VOLUME_NAME>

Using volumes on Linux

The example below illustrates the use of a volume without LVM.


Please note that this configuration is not suitable for production servers, but rather a demonstration that block volumes behave like regular disk drives attached to a server.

Once we have a command line that is connected via ssh to our instance, we check that our disk is recognized by the OS using fdisk:

$ sudo fdisk -l /dev/vdb
Disk /dev/vdb: 50 GiB, 53687091200 bytes, 104857600 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Now use fdisk to create a partition on the disk:

$ sudo fdisk /dev/vdb

Welcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x1552cd32.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-104857599, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-104857599, default 104857599):

Created a new partition 1 of type 'Linux' and of size 50 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Check the partition using lsblk:

$ lsblk
vda    253:0    0  10G  0 disk
└─vda1 253:1    0  10G  0 part /
vdb    253:16   0  50G  0 disk
└─vdb1 253:17   0  50G  0 part

Make a new filesystem on the partition:

$ sudo mkfs.ext4 /dev/vdb1
mke2fs 1.42.13 (17-May-2015)
Creating filesystem with 5242624 4k blocks and 1310720 inodes
Filesystem UUID: 7dec7fb6-ff38-453b-9335-xxxxxxxxxxxx
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

Create a directory where you wish to mount this file system:

$ sudo mkdir /mnt/extra-disk

Mount the file system:

$ sudo mount /dev/vdb1 /mnt/extra-disk

Label the partition:

$ sudo tune2fs -L 'extra-disk' /dev/vdb1
tune2fs 1.42.13 (17-May-2015)
$ sudo blkid
/dev/vda1: LABEL="cloudimg-rootfs" UUID="98c51306-83a2-49da-94a9-xxxxxxxxxxxx" TYPE="ext4" PARTUUID="8cefe526-01"
/dev/vdb1: LABEL="extra-disk" UUID="7dec7fb6-ff38-453b-9335-xxxxxxxxxxxx" TYPE="ext4" PARTUUID="235ac0e4-01"

If you want the new file system to be mounted when the system reboots then you should add an entry to /etc/fstab. For example, making sure you have sudo privilege:

$ cat /etc/fstab
LABEL=cloudimg-rootfs /               ext4    defaults    0 1
LABEL=extra-disk      /mnt/extra-disk ext4    defaults    0 2


When referring to block devices in /etc/fstab it is recommended that UUID or volume label is used instead of using the device name explicitly. It is possible for device names to change after a reboot, particularly when there are multiple attached volumes.