Re: [Xen-users] Exporting a PCI Device

[Jan Kalcic <jandot@xxxxxxxxxxxxxx>]

Joris Dobbelsteen wrote:
>> -----Original Message-----
>> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
>> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Jan Kalcic
>> Sent: Monday, 18 February 2008 12:02
>> To: deshantm@xxxxxxxxx
>> Cc: xen-users@xxxxxxxxxxxxxxxxxxx
>> Subject: Re: [Xen-users] Exporting a PCI Device
>>
>> Todd Deshane wrote:
>>     
>>> Hi,
>>>
>>> On Feb 17, 2008 6:34 PM, Jan Kalcic <jandot@xxxxxxxxxxxxxx 
>>> <mailto:jandot@xxxxxxxxxxxxxx>> wrote:
>>>
>>>     Hi All,
>>>
>>>     just a quick question I could not figure out. Is there a way to
>>>     export a
>>>     PCI device to multiple VMs (para) keeping it available 
>>>       
>> to dom0? Xen
>>     
>>>     version is 3.0.4.
>>>
>>>
>>> As far as I know you can't. That is what virtual devices are 
>>>       
>> used for 
>>     
>>> right?
>>>
>>> In what scenario would you want to grant direct access to a 
>>>       
>> PCI device 
>>     
>>> in VMs and also in dom0?
>>>
>>>       
>> Hi Todd,
>>
>> the PCI device which I would need to "share" is the fibre 
>> channel card connected to two different storage, on of this is 
>> the VMs repository which has to be visible to dom0 and the 
>> other one is the data storage for VMs which, obviously, has to 
>> be visibile to VMs. So the solution would be using two 
>> different fibre channel cards, right?
>>     
>
> What I would do is make all storage available to the dom0 and use
> regular methods to export it to the domU.
> In other words: treat dom0 as a very fancy piece of hardware that's
> between your kernel and the fibre-channel attached storage. For generic
> solutions the Virtual Block Device should be fast enough, otherwise you
> should probably consider a separate server, dedicated to that single
> task.
>
> I don't know if you are going to loose any fibre-channel advantages, but
> I figure you also reduce administrative complexity to dom0's only.
>
>   

I did some test and actually it's quite slow both in reading and in
writing. Roughly 50% as Block Device attacched to the domU.
It reduces complexity but too much is lost in performance.

Thanks,
Jan
> - Joris
>
>
>   


_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users