Exporting "SD" device.

Exporting "SD" device.

[P M, Priya]

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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.

If we use

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

/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??? 

Thanks.


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Re: Exporting "SD" device.

[Leeman Strout]

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On 6/13/06, P M, Priya <pm.priya@hp.com> wrote:
>
>  Hi,
>
>
> If we use
>
> disk = [ 'file:/home/adteam/linux_fc5_2.6.16,ioemu:hda,w',*'phy:/dev/sdd
> ,/dev/sdb,w'* ]
>
> /dev/sdb, then the device is not seen on domain 1.
>

This is just a guess, but you might try using the sda device instead.  Last
I used SCSI the Linux kernel squashed all SCSI id's to the beginning.  This
means that even if you had 1 device marked with SCSI ID 3, it showed up as
/dev/sda.  You are presenting the kernel with a virtual SCSI device and it
is likely presenting it as the first SCSI device available: /dev/sda while
you are telling xen to mount /dev/sdb.


Leeman

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Re: Exporting "SD" device.

[Anthony Liguori]

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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