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Create and configure an additional disk on an instance

This guide explains how to create an additional disk and then configure it on one of your instances.

Last updated 14th November 2019


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.

This guide explains how to create an additional disk and then configure it on one of your instances.



Firstly, log in to the OVHcloud Control Panel and click the Public Cloud menu. Then click on the Project you want to create the instance.

Now click the Actions button and then select Create a volume.

select project

Now configure you options for disk type, disk size, and location. When you've finished, click the Add button.

create disk

The new disk will now be displayed in your control panel.

configure disk

To attach the disk to an instance, click on the 3 dots on the right and then select Attach to instance

attach disk 01

Now choose the instance and click in Confirm button to attach the disk.

attach disk 02

The process of attaching the disk to your instance will now start and it may take several minutes to complete.

attach disk 03

You must ensure that you don’t navigate away from the Infrastructure tab while the disk is being attached. This could disrupt the process.

Using Linux

First, establish an SSH connection to your instance and then use the command below to list the instance's disks.

# admin@serveur-1:~$ lsblk

vda 254:0 0 10G 0 disk
└─vda1 254:1 0 10G 0 part /
vdb 254:16 0 10G 0 disk

VDA usually refers to your instance's default hard disk. VDB refers to the additional disk.

Next, create a partition on the additional disk using the command below.

# admin@serveur-1:~$ 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.

Next, format the partition using the command below.

# admin@serveur-1:~$ 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

Next, mount the partition with this command:

admin@serveur-1:~$ sudo mkdir /mnt/disk
admin@serveur-1:~$ sudo mount /dev/vdb1 /mnt/disk/

And finally, check the mount point using this command:

admin@serveur-1:~$ 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

If you want to create a persistent mount point, you will need to change the /etc/fstab. First, use the command below to retrieve the block ID.

admin@serveur-1:~$ 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"

And now you can use the block ID to change the /etc/fstab file.

admin@serveur-1:~$ vim /etc/fstab

/etc/fstab: static file system information.

# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point> <type> <options> <dump> <pass>
UUID=51ba13e7-398b-45f3-b5f3-fdfbe556f62c / ext4 defaults 0 0
UUID=2e4a9012-bf0e-41ef-bf9a-fbf350803ac5 /mnt/disk ext4 nofail 0 0

Using Windows

First, right-click on the Start Menu button and then click Disk Management.

disk management

When the disk management tool opens you'll see your new disk as an unknown volume with unallocated space as shown below.

unknown volume

Initialising the disk using Disk Management

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

offline disk

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

offline disk

Next, select MBR and click OK.

initialise disk

Initialsing the disk using DISKPART

First, right-click on the Start Menu button and then click Run

initialise disk

Next, type cmd in the Run prompt and then click OK

run prompt

At the command prompt, type the following command to open the DISKPART utility.

C:\> diskpart

Next, change the disk policy with the following series of commands.


SAN Policy : Offline Shared
DISKPART> san policy = OnlineAll

DiskPart successfully changed the SAN policy for the current operating system . [/ Code]

- 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.

Format the disk

Open up the Disk Management utility again, right-click the volume, then click New Simple Volume...

format disk

Now click Next.

format disk

Now set the desired disk size. You would usually want this to be 100% of the space. When you've done this, click Next.

format disk

Select a letter from the dropdown list to identify the drive, then click Next.

format disk

Select the options you want for the disk then click Next to perform the format operation.

format disk

Finally, click Finish to finalise the operation.

format disk

Once the disk is formatted, you can simply access it from File Explorer.

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