How to create and configure an additional disk on an instance

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Find out how to attach a new volume to your Public Cloud instance

Objective

It is possible to create additional disks for your Public Cloud instances.
This can be useful in cases where:

You want to increase your storage capacity without changing the instance model.
You want to have a highly available, high-performance storage.
You want to move your storage as well as your data to another instance.
You want to prepare the environment if you want to use Terraform.

This guide explains how to create an additional disk and configure it on your instance.

Requirements

A Public Cloud Instance in your OVHcloud account
Administrative (sudo) access to your instance via SSH (Linux) or RDP (Windows)

OVHcloud Control Panel Access

Direct link:
Navigation path: Public Cloud > Select your project

Warning

This feature is currently not available for Metal instances.

Instructions

The different types of volumes

OVHcloud offers three types of Block Storage volumes, each tailored to specific needs in terms of performance, capacity, and cost. These solutions allow you to attach persistent storage volumes to your instances, ensuring a high level of reliability and availability. If the feature is available, encryption can be enabled when creating a volume, for all volume types except Classic Multi-Attach volumes in 3AZ regions.

Classic – 500 IOPS guaranteed

The Classic volume is a reliable, cost-effective storage solution, ideal for workloads requiring moderate performance. It offers 500 guaranteed IOPS, making it suitable for the following uses:

Hosting of classic web applications
Storage of small to medium-sized databases
Data backup and archiving

In 3AZ regions, Classic Volumes are regional services that use distributed erasure coding across multiple Availability Zones. This ensures data remains available without impact or downtime in the event of an AZ failure, provided the multi-attached resilient architecture conditions are met. For more information, please refer to our guide "Proper Usage and Limitations of Classic Multi-Attach Block Storage in 3AZ Regions".

High Speed Gen2 – 30 IOPS/GB and up to 20,000 IOPS

Generation 2 High Speed volumes are optimized for the most demanding workloads. Performance scales with volume size:

IOPS: 30 IOPS/GB (base 3,000 IOPS for 10–100 GB, up to 20,000 IOPS)
Throughput: 0.5 MB/s/GB (base 50 MB/s for 10–100 GB, up to 512 MB/s)
Maximum size: 12 TB

This type of volume is recommended for:

Big Data and real-time analysis
Artificial intelligence and machine learning
Large database processing and high-performance storage

Info

You can no longer order High Speed (Gen1) volumes via the OVHcloud Control Panel. They have been replaced by High Speed Gen2 volumes at the same price, with better performance for volumes above 100 GB. High Speed volumes remain available via the API, Terraform, and OpenStack.

Existing High Speed volumes remain supported. You can also change your Block Storage volume type to migrate them to Gen2.

Info

All volume types are also available in an encrypted version (LUKS). These volumes ensure data confidentiality without impacting performance. They are available through the OVHcloud Control Panel as well as via the tools presented in the next section, by specifying the type <volume_type>-luks.

Attaching a new volume

Via the OVHcloud Control Panel

Via Terraform

Via the Horizon interface

Via the OpenStack CLI

Via the OVHcloud CLI

Open Block Storage in the left-hand menu under Storage & backup.

In this section, click on the button Create a volume.

Follow the configuration steps to select the location, disk type, encryption and disk capacity options. Enter a name for the volume and confirm by clicking on Create volume.

Warning

Please note: Your volume must be created in the same region as the instance to which you want to attach it. If you create it in another region, you can delete it and recreate it in the correct region.

The new disk will now be displayed in the Control Panel.

To the right of the volume, click on the ... button, then select Attach to instance.

In the popup window, choose an instance from the list and click on Confirm to attach the disk.

The process of attaching the disk to your instance will now begin. This may take a few minutes to complete.

Warning

Make sure to not leave the current page in your OVHcloud Control Panel while the disk is being attached. This might interrupt the process.

Warning

Please note that the "high-speed-gen2" or "luks" volume types may not be available in all regions.

Types of volumes:

Classic
High-speed
High-speed-gen2
Classic-luks
High-speed-luks
High-speed-gen2-luks

The types ending in -luks are encrypted (LUKS).

Warning

Creating a -luks volume automatically generates a dedicated key.

Do not modify or delete this key if it is linked to a Block Storage volume. Doing so would make the data on that volume and all its snapshots permanently unrecoverable.

To create a simple block storage volume, you need 3 elements:

The name of the volume
The region
The size of the volume in GB

In our example, we will create a block storage in the GRA11 region with a size of 10 GB. Add the following lines to a file named simple_blockstorage.tf:

# Creation of a block storage volume
resource "openstack_blockstorage_volume_v3" "terraform_blockstorage" {
  name   = "terraform_blockstorage" # Name of the block storage volume
  size   = 10                       # Volume size
  region = "GRA11"                  # Region where the volume must be created
  volume_type = "volume_type"       # classic, high-speed, high-speed-gen2 or equivalent `-luks`
}

Then we will attach it to the target instance.

Warning

The instance and the volume must be in the same region.

Add the following lines below the previous ones:

# Attach the volume to the instance
resource "openstack_compute_volume_attach_v2" "volume_attach" {
  instance_id = "<your_instance_id>"
  volume_id   = openstack_blockstorage_volume_v3.terraform_volume.id
}

You can create your block storage volume and attach it to the desired instance by entering the following command:

terraform apply

The output should look like this:

$ terraform apply
Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # openstack_blockstorage_volume_v3.terraform_blockstorage will be created
  + resource "openstack_blockstorage_volume_v3" "terraform_blockstorage" {
      + attachment        = (known after apply)
      + availability_zone = (known after apply)
      + id                = (known after apply)
      + metadata          = (known after apply)
      + name              = "terraform_blockstorage"
      + region            = "GRA11"
      + size              = 10
      + volume_type       = "high-speed-gen2"
    }

  # openstack_compute_volume_attach_v2.volume_attach will be created
  + resource "openstack_compute_volume_attach_v2" "volume_attach" {
      + device      = (known after apply)
      + id          = (known after apply)
      + instance_id = "11cc1279-xxxx-xxxx-xxxx-3ace4c954780"
      + region      = (known after apply)
      + volume_id   = (known after apply)
    }

Plan: 2 to add, 0 to change, 0 to destroy.

Do you want to perform these actions in workspace "test_terraform"?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

openstack_blockstorage_volume_v3.terraform_blockstorage: Creating...
openstack_blockstorage_volume_v3.terraform_blockstorage: Still creating... [10s elapsed]
openstack_blockstorage_volume_v3.terraform_blockstorage: Creation complete after 12s [id=daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]
openstack_compute_volume_attach_v2.volume_attach: Creating...
openstack_compute_volume_attach_v2.volume_attach: Still creating... [10s elapsed]
openstack_compute_volume_attach_v2.volume_attach: Creation complete after 14s [id=11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]

Apply complete! Resources: 2 added, 0 changed, 0 destroyed.

Go to the Volumes drop-down section, click Volumes and then Create Volume.

Fill in the Volume Name field and select the type of volume you want. Then click on Create Volume

Warning

Please note that if the volume type "high-speed-gen2" or "luks" does not appear in the list, this means that it is not available in this region.

To attach this volume to an instance, on your volume line, click the arrow at the end of the line next to Edit Volume. Then click on Manage Attachments.

Attach a block storage volume to an instance

Select the instance to which you wish to attach your volume, then click on Attach Volume.

Attach a block storage volume to an instance 02

Warning

Please note that if the volume type "high-speed-gen2" or "luks" does not appear in the list, this means that it is not available in this region.

Types of volumes:

Classic
High-speed
High-speed-gen2
Classic-luks
High-speed-luks
High-speed-gen2-luks

The types ending in -luks are encrypted (LUKS).

Warning

Creating a -luks volume automatically generates a dedicated key.

Do not modify or delete this key if it is linked to a Block Storage volume. Doing so would make the data on that volume and all its snapshots permanently unrecoverable.

List the volume types available in the region:

openstack volume type list

Create a volume, specifying at least its size (in GB) and a type from those listed above. You can also specify a name for your volume at the end of the command.

openstack volume create --size 1 --type high-speed-gen2 volumeName # classic, high-speed, high-speed-gen2 or equivalent `-luks`

To attach a volume to an instance available in the region, use the following command:

openstack server add volume <server-id|server-name> <volume-id|volume-name>

+-----------+-------------------------------------+
| Field | Value |
+-----------+-------------------------------------+
| ID | 7d3d670f- ****-****-****-60dd1e6**** |
| Server ID | 74317f97-****-****-80cf2d4**** |
| Volume ID | 7d3d670f-****-****-****-60dd1e6**** |
| Device | /dev/sdb |
| Tag | None |
+-----------+-------------------------------------+

Warning

If the volume type "high-speed-gen2" or "luks" does not appear in the list, it is not available in this region.

Option	Description
`<region>`	Region where the volume will be created (e.g. `GRA11`)
`--name`	Volume name
`--size`	Volume size in GB
`--type`	Volume type: `classic`, `high-speed`, `high-speed-gen2`, or equivalent `-luks` variant
`--wait`	Wait for creation to complete before exiting

Create a volume by specifying the region, a name, the size in GB, and a type:

ovhcloud cloud storage block create <region> --name <volume-name> --size <size-in-GB> --type <volume-type> --wait

Once the volume is created, attach it to an instance:

Parameter	Description
`<volume_id>`	ID of the volume to attach
`<instance_id>`	ID of the instance to attach the volume to

ovhcloud cloud storage block attach <volume_id> <instance_id>

Configuring the new disk

The examples below presume you are logged in as a user with elevated permissions.

Using Linux

Establish an SSH connection to your instance, then use the command below to list the attached disks.

lsblk

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda 254:0 0 10G 0 disk
└─vda1 254:1 0 10G 0 part /
vdb 254:16 0 10G 0 disk

Info

vda in this example refers to the default disk of the instance. The additional disk will then be labelled vdb.

Create a partition on the additional disk using the commands below.

If your additional disk is less than 2TB:

sudo fdisk /dev/vdb

Welcome to fdisk (util-linux 2.25.2).
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 0x95c4adcc.

Command (m for help): n

Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (1-4, default 1):
First sector (2048-20971519, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-20971519, default 20971519):

Created a new partition 1 of type 'Linux' and of size 10 GiB.

Command (m for help): w

The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

If your additional disk is larger than 2TB:

sudo parted /dev/vdb

GNU Parted 3.5
Using /dev/vdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) help                                                             
  align-check TYPE N                       check partition N for TYPE(min|opt) alignment
  help [COMMAND]                           print general help, or help on COMMAND
  mklabel,mktable LABEL-TYPE               create a new disklabel (partition table)
  mkpart PART-TYPE [FS-TYPE] START END     make a partition
  name NUMBER NAME                         name partition NUMBER as NAME
  print [devices|free|list,all]            display the partition table, or available devices, or free space, or all found partitions
  quit                                     exit program
  rescue START END                         rescue a lost partition near START and END
  resizepart NUMBER END                    resize partition NUMBER
  rm NUMBER                                delete partition NUMBER
  select DEVICE                            choose the device to edit
  disk_set FLAG STATE                      change the FLAG on selected device
  disk_toggle [FLAG]                       toggle the state of FLAG on selected device
  set NUMBER FLAG STATE                    change the FLAG on partition NUMBER
  toggle [NUMBER [FLAG]]                   toggle the state of FLAG on partition NUMBER
  unit UNIT                                set the default unit to UNIT
  version                                  display the version number and copyright information of GNU Parted
(parted) mklabel gpt                                                      
(parted) mkpart primary 0 3750G                                           
Warning: The resulting partition is not properly aligned for best performance: 34s % 2048s != 0s
Ignore/Cancel? I                                                          
(parted) quit

Next, format the new partition vdb1 using the command below.

sudo mkfs.ext4 /dev/vdb1

mke2fs 1.42.12 (29-Aug-2014)
Creating filesystem with 2621184 4k blocks and 655360 inodes
Filesystem UUID: 781be788-c4be-462b-b946-88429a43c0cf
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

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

Mount the partition with the following commands:

sudo mkdir /mnt/disk

sudo mount /dev/vdb1 /mnt/disk/

Finally, check the mount point using this command:

df -h

Filesystem Size Used Avail Use% Mounted on
/dev/vda1 9.8G 840M 8.6G 9% /
udev 10M 0 10M 0% /dev
tmpfs 393M 5.2M 388M 2% /run
tmpfs 982M 0 982M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 982M 0 982M 0% /sys/fs/cgroup
/dev/vdb1 9.8G 23M 9.2G 1% /mnt/disk

Info

The mounting is not persistent because the disk will be detached when the instance reboots. In order to automate the mounting process, the fstab file needs to be edited.

First, retrieve the UUID (block ID) of the new volume:

sudo blkid

/dev/vda1: UUID="51ba13e7-398b-45f3-b5f3-fdfbe556f62c" TYPE="ext4" PARTUUID="000132ff-01"
/dev/vdb1: UUID="2e4a9012-bf0e-41ef-bf9a-fbf350803ac5" TYPE="ext4" PARTUUID="95c4adcc-01"

Open /etc/fstab with a text editor:

sudo nano /etc/fstab

Add the line below to the file and replace the UUID with your own:

UUID=2e4a9012-bf0e-41ef-bf9a-fbf350803ac5 /mnt/disk ext4 nofail 0 0

Save and exit the editor. The disk should be automatically mounted after every reboot from now on.

Using Windows

Establish a remote desktop (RDP) connection to your Windows instance.

Once logged in, right-click on the Start Menu button and open Disk Management.

The new disk will be displayed as an unknown volume with unallocated space.

If the disk is marked as offline here, it needs to be initialised first. You can use the Windows GUI or the DISKPART utility to achieve this. Otherwise, proceed with formatting the disk in Disk Management.

Initialising the disk in Disk Management

Right-click on the disk and select Online.

If the disk is marked as offline here, this is likely due to a policy in place on the instance. To fix this, right-click on the disk and select Online.

Then right-click it again and this time select Initialise Disk.

Next, select MBR if your additional disk is less than 2TB, or GPT if it is more than 2TB, then click OK.

Initialising the disk with DISKPART

Right-click on the Start Menu button and open Run.

Type cmd and click OK to open the command line application.

At the command prompt, open DISKPART:

C:\> diskpart

Use the following series of DISKPART commands to set the disk to online:

DISKPART> san

SAN Policy : Offline Shared

DISKPART> san policy = OnlineAll

DiskPart successfully changed the SAN policy for the current operating system .

- Implementation of the strategy on the extra disk:
[Code] DISKPART> list disk

Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 200 GB 0 B
* Disk 1 Offline 10 GB 1024 KB

DISKPART> select disk 1

Disk 1 is now the selected disk.

DISKPART> attributes disk clear readonly

Disk attributes cleared successfully.

DISKPART> attributes disk

Current Read-only State : No
Read-only : No
Boot Disk : No
Pagefile Disk : No
Hibernation File Disk : No
Crashdump Disk : No
Clustered Disk : No

DISKPART> online disk

DiskPart successfully onlined the selected disk.

Formatting the disk

In Disk Management, right-click on the new disk and select New Simple Volume....

In the wizard, click Next to specify the volume size. It should be set to maximum by default. Click Next to continue.

Leave the new drive letter at default or select a different one, then click Next.

Label the volume (optional) and confirm the formatting options by clicking Next.

In the last window, click Finish to format the disk.

The disk will be available as a drive in File Explorer after the operation.

Detach a volume

If you wish to detach a volume from your instance, the best practice is to unmount the volume in the operating system before detaching it from the instance.

Warning

An error message may appear if you have software or processes running on the additional disk. In this case, it is recommended to stop all processes before continuing.

Here's how to unmount the volume from the operating system before detaching it from the instance :

On Linux

On Windows

Establish an SSH connection to your instance, then use the command below to list the attached disks.

lsblk

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda 254:0 0 10G 0 disk
└─vda1 254:1 0 10G 0 part /
vdb       8:0    0   10G  0 disk
└─vdb1    8:1    0   10G  0 part /mnt/disk

Unmount the partition using the command below:

sudo umount /dev/vdb1

Remove the device ID from the fstab to complete the unmount process, if this is not done, the partition will be mounted right back after a reboot.

sudo nano /etc/fstab

Save and exit the editor.

Finally, we will detach the volume from the instance:

Via the OVHcloud Control Panel

Via Terraform

Via the OVHcloud CLI

Go to the Public Cloud section of your OVHcloud Control Panel and click on Block Storage in the left-hand menu under Storage & backup.

Click the ... button next to the corresponding volume and select Detach from instance.

Click on Confirm in the pop up window to start the process.

Start by deleting the lines previously created in your Terraform file:

# Attach the volume to the instance
resource "openstack_compute_volume_attach_v2" "volume_attach" {
  instance_id = "<your_instance_id>"
  volume_id   = openstack_blockstorage_volume_v3.terraform_volume.id
}

Enter the following command to check whether the correct resource will be deleted:

terraform plan

The output should look like this:

$ terraform plan
openstack_compute_volume_attach_v2.va_1: Refreshing state... [id=11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]
openstack_blockstorage_volume_v3.terraform_volume: Refreshing state... [id=daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  - destroy

Terraform will perform the following actions:

  # openstack_compute_volume_attach_v2.va_1 will be destroyed
  # (because openstack_compute_volume_attach_v2.va_1 is not in configuration)
  - resource "openstack_compute_volume_attach_v2" "va_1" {
      - device      = "/dev/sdb" -> null
      - id          = "11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806" -> null
      - instance_id = "11cc1279-xxxx-xxxx-xxxx-3ace4c954780" -> null
      - region      = "GRA11" -> null
      - volume_id   = "daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806" -> null
    }

Plan: 0 to add, 0 to change, 1 to destroy.

Then apply the changes by entering this command:

terraform apply

The output should look like this:

$ terraform apply
openstack_compute_volume_attach_v2.va_1: Refreshing state... [id=11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]
openstack_blockstorage_volume_v3.terraform_volume: Refreshing state... [id=daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  - destroy

Terraform will perform the following actions:

  # openstack_compute_volume_attach_v2.va_1 will be destroyed
  # (because openstack_compute_volume_attach_v2.va_1 is not in configuration)
  - resource "openstack_compute_volume_attach_v2" "va_1" {
      - device      = "/dev/sdb" -> null
      - id          = "11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806" -> null
      - instance_id = "11cc1279-xxxx-xxxx-xxxx-3ace4c954780" -> null
      - region      = "GRA11" -> null
      - volume_id   = "daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806" -> null
    }

Plan: 0 to add, 0 to change, 1 to destroy.

Do you want to perform these actions in workspace "test_terraform"?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

openstack_compute_volume_attach_v2.va_1: Destroying... [id=11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806]
openstack_compute_volume_attach_v2.va_1: Still destroying... [id=11cc1279-xxxx-xxxx-xxxx-3ace4c954780/daf3a86e-xxxx-xxxx-xxxx-ac7b6ffbb806, 10s elapsed]
openstack_compute_volume_attach_v2.va_1: Destruction complete after 17s

Apply complete! Resources: 0 added, 0 changed, 1 destroyed.

Parameter	Description
`<volume_id>`	ID of the volume to detach
`<instance_id>`	ID of the instance to detach the volume from

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Increasing the size of an additional disk

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