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.

../_images/volume-page.png

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

../_images/create-vol.png

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.

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.

../_images/manage-attachments.png

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.

../_images/attach-to-instance.png

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

Creating a volume via from the command line

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

Note

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

The following script will create a volume on your project:

create-volume.sh
$ 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-a200e963404a |
| 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             | 4b934c44d8b24e60acad9609b641bee3     |
+---------------------+--------------------------------------+

The next script 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.

attach-volume.sh
$ openstack server add volume <INSTANCE_NAME> <VOLUME_NAME>

The following assumes that you have already sourced an openRC file and that you have downloaded and installed terraform.

The template file that you need to save is:

terraform-block-storage.tf
# Configure the OpenStack Provider
# This example relies on OpenStack environment variables
# If you wish to set these credentials manualy please consult
# https://www.terraform.io/docs/providers/openstack/index.html
provider "openstack" {
}

variable "public_network_id" {
  default = "<INSERT YOUR REGION NETWORK ID FROM THE BELOW LIST>"
}

# From: http://docs.catalystcloud.io/network.html?highlight=public%20network
#nz-por-1	849ab1e9-7ac5-4618-8801-e6176fbbcf30
#nz_wlg_2	e0ba6b88-5360-492c-9c3d-119948356fd3
#nz-hlz-1	f10ad6de-a26d-4c29-8c64-2a7418d47f8f

variable "volume_image_ID" {
  default = "<INSERT THE UBUNTU 20.0 IMAGE ID FROM YOUR REGION>"
}

variable "instance_id" {
  default = "<INSERT INSTANCE ID>"
}

variable "volume_type" {
  default = "b1.standard"
}

#-----------------------------------------------------------------------------------------------

#Create an NVME storage volume
resource "openstack_blockstorage_volume_v2" "testvol" {
  size          = 50
  image_id      = "${var.volume_image_ID}"
  volume_type   = "${var.volume_type}"
}

#Explicitely attach the storage volume to the instance
resource "openstack_compute_volume_attach_v2" "va_1" {
  instance_id = "${var.instance_id}"
  volume_id   = "${openstack_blockstorage_volume_v2.testvol.id}"

The commands you will need to use are:

terraform-create.sh
$ terraform init

----------------------------------------------

$ terraform plan

----------------------------------------------

$ terraform apply

To remove all resources associated with this terraform plan, you can use the following:

terraform-destroy.sh
terraform destroy

Using volumes on Linux

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

Warning

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
NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
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-9335-0c240d179262
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
    4096000

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-94a9-2a841c9f27b0" TYPE="ext4" PARTUUID="8cefe526-01"
/dev/vdb1: LABEL="extra-disk" UUID="7dec7fb6-ff38-453b-9335-0c240d179262" 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

Note

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.