ISCSI boot limitation in HVM hosts

ISCSI boot limitation in HVM hosts

[Guillaume Rousse]

Hello list.

I just ran into the issue of unability to boot from a device exported as 
/dev/sda in a HVM host, as described at 
http://www.bestgrid.org/index.php/HVM_virtual_machine

As even IDE drives are now labeled 'sda' also with recent linux kernels, 
this is a bit troublesome :)

-- 
BOFH excuse #309:

firewall needs cooling

Re: ISCSI boot limitation in HVM hosts

[Keir Fraser]

On 04/02/2009 10:51, "Guillaume Rousse" <Guillaume.Rousse@inria.fr> wrote:

> I just ran into the issue of unability to boot from a device exported as
> /dev/sda in a HVM host, as described at
> http://www.bestgrid.org/index.php/HVM_virtual_machine
> 
> As even IDE drives are now labeled 'sda' also with recent linux kernels,
> this is a bit troublesome :)

The limitation is that the BIOS cannot boot from SCSI discs. It can boot
from any IDE disc, regardless of what Linux calls it.

 -- Keir

Re: ISCSI boot limitation in HVM hosts

[Daniel P. Berrange]

On Wed, Feb 04, 2009 at 11:29:47AM +0000, Keir Fraser wrote:
> On 04/02/2009 10:51, "Guillaume Rousse" <Guillaume.Rousse@inria.fr> wrote:
> 
> > I just ran into the issue of unability to boot from a device exported as
> > /dev/sda in a HVM host, as described at
> > http://www.bestgrid.org/index.php/HVM_virtual_machine
> > 
> > As even IDE drives are now labeled 'sda' also with recent linux kernels,
> > this is a bit troublesome :)
> 
> The limitation is that the BIOS cannot boot from SCSI discs. It can boot
> from any IDE disc, regardless of what Linux calls it.

In upstream QEMU there is a 'extboot' option ROM that lets it boot off any
IDE, SCSI, or VirtIO disk. It'd be good to get that working under Xen HVM,
and also have it support Xen PV block, so you can avoid any restrictions
on disk configs in HVM.

Daniel
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