---
features:
  - |
    A new microversion has been added to allow fully-asynchronous attachment of
    volumes to a server. Previously, calling ``POST
    /servers/{server_id}/os-volume_attachments`` to attach a volume would
    return HTTP 200 containing a ``volumeAttachment`` object, returning a
    device name. With API version 2.101 this changes to HTTP 202. The reason
    is, that the device name could not be assured by any of the current drivers
    and reserving the device name could block the API thread for some time.