Using SCSI and IDE frontend devices

Using SCSI and IDE frontend devices

[Glauber de Oliveira Costa]

Hello,

>From my comprehension, (correct me if I'm wrong), xvd frontend devices
should be used instead of hd and sd devices in the medium/long term. By
now, using sd devices does not even seems to always work. Shouldn't it
be te case for us to deprecate it's usage?

I got a simple patch that does it in case it's of interest, but some
questions still remains, like: Is leaving the message enough, or can we
do better, by making sure a xvd is used, even if it was not requested?

Comments very welcome,


-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

Re: Using SCSI and IDE frontend devices

[Ewan Mellor]

On Wed, Oct 25, 2006 at 02:53:13PM -0300, Glauber de Oliveira Costa wrote:

> Hello,
> 
> >From my comprehension, (correct me if I'm wrong), xvd frontend devices
> should be used instead of hd and sd devices in the medium/long term. By
> now, using sd devices does not even seems to always work. Shouldn't it
> be te case for us to deprecate it's usage?
> 
> I got a simple patch that does it in case it's of interest, but some
> questions still remains, like: Is leaving the message enough, or can we
> do better, by making sure a xvd is used, even if it was not requested?

It's the case that we want to deprecate sd and hd in the case of PV Linux, but
for HVM, we use the hd names to communicate with QEMU, and that's not a
problem because the guest doesn't see the device in the same way, and for
non-Linux PV guests, they are welcome to do whatever they want in terms of
device numbers.

For those reasons, we certainly can't force xvd when it wasn't requested.  We
even can't force it for Linux PV, as this would break older guests.

I think deprecation by documentation only is probably the best way.

Ewan.