nova/doc/api_samples/os-volumes/attach-volume-to-server-resp.json

{
    "volumeAttachment": {
        "device": "/dev/sdb",
        "id": "a07f71dc-8151-4e7d-a0cc-cd24a3f11113",
        "serverId": "802db873-0373-4bdd-a433-d272a539ba18",
        "volumeId": "a07f71dc-8151-4e7d-a0cc-cd24a3f11113"
    }
}