Block Storage

Attach persistent block storage volumes to your Public Cloud instances for databases, file systems, and high-performance workloads.

Block Storage lets you attach persistent volumes directly to your Public Cloud instances. Unlike object storage — where data is accessed via HTTP APIs as discrete objects — block storage behaves like a physical disk: you partition it, format it with a filesystem, and mount it at a path in your OS.

Create and attach a volume

Create a volume in the Control Panel and attach it to a running instance.

Format and mount on Linux

Partition, format, and persistently mount a new volume on Linux.

Volume snapshots

Take point-in-time snapshots to protect your data.

Performance tiers

Choose between Classic, High Speed, and Regional Classic volumes.

Overview

Block storage vs object storage

	Block Storage	Object Storage
Access method	Mounted as a local disk (via OS)	HTTP/S3 API
Use cases	Databases, VMs, filesystems	Backups, static assets, data lakes
Filesystem support	ext4, XFS, NTFS, etc.	Not applicable
Scalability	Up to 12 TB per volume	Unlimited
Latency	Very low (NVMe)	Higher (network)
Shareable	Limited (Multi-Attach on specific tiers)	Yes (via ACLs/policies)

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Performance tiers

OVHcloud Block Storage is available in three classes, each suited to different workloads.

Classic Volume

Backed by NVMe over Fabric with 500 IOPS guaranteed and 64 MB/s throughput. Data is replicated within a single availability zone (1-AZ) or Local Zone.

Best for: web application databases, VM storage, and backups where multi-zone redundancy is not required.

Regional Classic Volume

Also delivers 500 IOPS guaranteed and 64 MB/s, but data is automatically replicated across three availability zones (3-AZ) within the same region. Supports Multi-Attach, meaning you can attach the same volume simultaneously to multiple instances in different AZs.

SLA: 99.99% availability.

Best for: critical databases and distributed applications that require high availability and resilience.

High Speed Volume

Available in two generations:

Generation	IOPS	Throughput
Gen 1	Up to 3,000 IOPS	Up to 128 MB/s
Gen 2	30 IOPS/GB (max 20,000 IOPS)	0.5 MB/s per GB (max 512 MB/s)

Best for: transactional databases, analytics, AI/ML workloads, and any application requiring maximum I/O.

Comparison

Storage class	IOPS	Throughput	Availability	Replication
Classic Volume	500 guaranteed	64 MB/s	99.9%	Single AZ
Regional Classic	500 guaranteed	64 MB/s	99.99%	3-AZ (multi-zone)
High Speed Gen 1	Up to 3,000	128 MB/s	99.9%	Single AZ
High Speed Gen 2	Up to 20,000	Up to 512 MB/s	99.9%	Single AZ

All volume types are also available as encrypted variants using LUKS. Specify the type with the -luks suffix (e.g. classic-luks, highspeed-luks). Encryption has no performance impact. Regional Classic and Local Zone volumes do not support LUKS encryption.

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Create and attach a volume

1. Create the volume

   In the OVHcloud Control Panel, go to Public Cloud > your project > Block Storage in the left-hand menu under Storage & backup.

   Click Create a volume and choose:

   • Location: must match the region of the instance you want to attach the volume to
   • Volume type: Classic, High Speed Gen 1, or High Speed Gen 2
   • Encryption: optionally enable LUKS encryption
   • Capacity: 10 GB to 12 TB

   Click Create volume.

   Your volume and instance must be in the same region. A volume cannot be attached across regions.

2. Attach the volume to an instance

   On the volume list, click the ... button next to your volume and select Attach to instance.

   In the pop-up, choose the target instance and click Confirm. The attachment takes a few minutes.

   You can also attach via the OpenStack CLI:

   openstack server add volume <server-id> <volume-id>
   
3. Format and mount on Linux

   SSH into your instance. List attached disks to identify the new volume:

   lsblk
   

   You should see a new device such as /dev/vdb. Proceed to format and mount it — see the Format and mount on Linux section below.

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Format and mount on Linux

1. Identify the new device

   lsblk
   

   Example output:

   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   50G  0 disk
   

   The new volume appears as vdb (the name may differ on your instance).

2. Create a partition

   For volumes under 2 TB, use fdisk:

   sudo fdisk /dev/vdb
   

   At the prompt, type n to create a new partition, accept the defaults, then type w to write and exit.

   For volumes over 2 TB, use parted:

   sudo parted /dev/vdb
   (parted) mklabel gpt
   (parted) mkpart primary 0 100%
   (parted) quit
   
3. Format the partition

   sudo mkfs.ext4 /dev/vdb1
   
4. Mount the partition

   sudo mkdir /mnt/disk
   sudo mount /dev/vdb1 /mnt/disk/
   

   Verify the mount:

   df -h
   
5. Make the mount persistent across reboots

   Retrieve the UUID of the partition:

   sudo blkid
   

   Example output:

   /dev/vdb1: UUID="2e4a9012-bf0e-41ef-bf9a-fbf350803ac5" TYPE="ext4"
   

   Open /etc/fstab and add the following line, replacing the UUID with your own:

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

   Save and close the file. The volume will now mount automatically on reboot.

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Detach and reattach volumes

Unmount before detaching

Always unmount the volume from the OS before detaching it from the instance to avoid data corruption.

sudo umount /dev/vdb1

Remove the entry from /etc/fstab if the mount is persistent, then detach the volume from the Control Panel or via CLI:

openstack server remove volume <server-id> <volume-id>

Reattach to another instance

Once detached, attach the volume to a different instance from the Control Panel or CLI:

openstack server add volume <new-server-id> <volume-id>

Mount it again on the new instance using the same steps as initial mounting. The filesystem and data are preserved.

You can use volume detach and reattach to migrate data between instances without copying files over the network.

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Volume snapshots

A snapshot captures the state of a volume at a given point in time. Snapshots are stored on Block Storage and may incur additional storage charges.

Create a snapshot from the Control Panel

In Block Storage, click the ... button on a volume and select Create a snapshot. Give it a name and confirm. Snapshots are available within a few minutes.

Create a snapshot via CLI

openstack volume snapshot create \
  --volume <volume-id> \
  --name my-snapshot

Restore from a snapshot

Create a new volume from a snapshot:

openstack volume create \
  --snapshot <snapshot-id> \
  --size <size-in-GB> \
  my-restored-volume

For consistent snapshots of volumes that host databases or active workloads, consider quiescing writes or using your database’s flush/lock commands before taking the snapshot.

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Shared responsibility model

Responsibility	You	OVHcloud
Choosing the volume type and sizing	Yes
Formatting, mounting, and managing the filesystem	Yes
Data encryption (LUKS) configuration	Yes
Managing backups and snapshots	Yes
Data security and access control on the volume	Yes
Maintaining physical hardware and storage infrastructure		Yes
Operating the block storage cluster and control plane		Yes
Network connectivity between volume and instance		Yes
Replication and durability at the storage layer		Yes

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Related guides

Object Storage

Store files and backups at scale using the S3-compatible API.

vRack — Private Network

Connect block storage workloads to other OVHcloud services privately.