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Migrating a Block Storage volume to an encrypted LUKS volume

Stephanie R.
Updated

Learn how to migrate your data from a standard Block Storage volume to a new LUKS-encrypted volume by creating a new volume and copying your data across safely.

OVHcloud now offers Block Storage volumes encrypted with LUKS. Currently, it is not possible to directly convert an existing volume to a LUKS-encrypted one using the retype option, nor to back up and restore it as a LUKS volume.

 

Requirements

  • A Public Cloud instance in your OVHcloud account
  • An existing Block Storage volume (source)
  • Administrator (root or sudo) access to your instance

OVHcloud Control Panel Access

 

Instructions

Step 1: Create a LUKS volume

In your OVHcloud Control Panel, create a new Block Storage volume and select the LUKS type.

Once attached to your instance, the LUKS volume behaves like a standard volume. All encryption and unlocking are handled automatically by the OVHcloud infrastructure.

 

Step 2: Attach the volumes to your instance

  1. Attach both volumes to your instance:
    • Source volume (non encrypted)
    • Target volume (LUKS encrypted)

  2. Verify that both volumes are visible on your instance:

    bash lsblk

    Example output:

    bash /dev/vdb # source volume /dev/vdc # target LUKS volume

 

Step 3: Prepare the LUKS (encrypted) volume

  1. Format the LUKS volume with the filesystem of your choice (for example, ext4):

    bash sudo mkfs.ext4 /dev/vdc

  2. Mount the target volume:

    bash sudo mkdir -p /mnt/luks_target sudo mount /dev/vdc /mnt/luks_target

 

Step 4: Mount the source volume

If not already mounted, mount the source volume to your instance:

sudo mkdir -p /mnt/source_volume
sudo mount /dev/vdb /mnt/source_volume

 

Step 5: Copy the data

Use rsync to copy your data from the source volume to the LUKS-encrypted target volume while preserving permissions and attributes:

# Copy data while preserving permissions and attributes
sudo rsync -aAXHv /mnt/source_volume/ /mnt/luks_target/

# Or, with progress display for large volumes
sudo rsync -aAXHv --progress /mnt/source_volume/ /mnt/luks_target/

 

Step 6 (Optional): Verify and detach

  1. Verify that your data has been copied successfully. You can use commands like ls, du, or rsync --dry-run for quick checks.

  2. Unmount both volumes:

    bash sudo umount /mnt/source_volume sudo umount /mnt/luks_target
  3. Detach the source volume if it is no longer needed.

 

Step 7 (Optional): Update your mount points

If the LUKS volume should be used permanently, add an entry to /etc/fstab to mount it automatically at boot.

Example:

UUID=<UUID_of_volume> /mnt/data ext4 defaults 0 2

Notes:

Replace with the actual UUID of your LUKS volume (obtain it with sudo blkid /dev/vdc).

Ensure the mount point /mnt/data exists before boot or the system may fail to mount the volume.

 

Go further

For more information and tutorials, please see our other Public Cloud support guides or explore the guides for other OVHcloud products and services.

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