Re: Exporting "SD" device.

[Anthony Liguori <aliguori@us.ibm.com>]

P M, Priya wrote:
> Hi,
>  
> We have Intel VT enabled system loaded with Xen 3.0.2 and qemu based 
> FC5+linux 2.6.16 as a guest operating system. We want to export the 
> disk to the domain 1 (FC5_linux 2.6.16) as "SD" device. But we are not 
> able to export the SCSI disk as a SD device, we could export as a "HD" 
> device.
>  
> In the Configuration file,
>
> disk = [ 
> 'file:/home/adteam/linux_fc5_2.6.16,ioemu:hda,w',*'phy:/dev/sdd,ioemu:hdb,w'* 
> ]
>
> if we use ioemu:hdb, then the device is exported to the domain 1 and 
> we could see the device.
>

ioemu:hdb is the syntax for FV devices.  For FV, we only currently 
support exposing as IDE devices.

> If we use
>
> disk = [ 
> 'file:/home/adteam/linux_fc5_2.6.16,ioemu:hda,w',*'phy:/dev/sdd,/dev/sdb,w'* 
> ]
>

This is only valid syntax for PV domains.

> /dev/sdb, then the device is not seen on domain 1.
>
> Are we missing something. Is it not possible to export an SD device to 
> domain 1? Is there any limitiation in qemu based domain 1, because our 
> domain 0 is qemu based operating system.
>
> Is there any performance difference between "hda" and "sda" exported 
> devices???
>

There is no support for SCSI emulator ATM.  It is on the Roadmap though 
and it ought to have a pretty significant performance impact.  It's 
going to take a fair bit of time to realize that though.

Regards,

Anthony Liguori

> Thanks.
>
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