Open Stack

On 05/26/2015 03:13 AM, Daniel P. Berrange wrote:
> On Sat, May 23, 2015 at 11:00:32AM +0200, Géza Gémes wrote:
>> Hi,
>>
>> When someone calls nova volume-attach or the block-device-mapping parameter
>> at boot, it is possible to specify a device name for the guest. However I
>> couldn't find any guest OS which would honor this. E.g. with libvirt/kvm, if
>> the guest has two virtio disks already (vda and vdb), specifying vdf would
>> be ignored and the disk will be attached as vdc in the guest.
>> I propose to deprecate this option and at boot where it is not optional to
>> accept only auto as an option.
>
> This was a design mistake in the original API which we can't now remove
> without breaking backcompatibility. While it is still supported, many
> hypervisors will completely ignore it, so we discourage people from ever
> using it. Just allow the hypervisor and/or guest OS to pick the device
> name

While Dan is correct that we cannot just remove the parameter from the 
Nova API, we *can* add a microversion that removes the parameter from 
the accepted list of parameters for POST /servers and returns an error 
when the client has sent both an X-OpenStack-Compute-API-Version value 
 >= the microversion increment *and* the device name parameter.

Best,
-jay