Re: [Xen-devel] Virtualization project idea

[Michal Novotny <minovotn@xxxxxxxxxx>]

On 08/27/2010 03:33 PM, Pasi Kärkkäinen wrote:
> On Fri, Aug 27, 2010 at 03:26:46PM +0200, Michal Novotny wrote:
>    
> > On 08/27/2010 03:22 PM, Pasi Kärkkäinen wrote:
> >      
> > > On Fri, Aug 27, 2010 at 03:18:01PM +0200, Christoph Egger wrote:
> > >
> > >        
> > > > On Friday 27 August 2010 15:08:47 Pasi Kärkkäinen wrote:
> > > >
> > > >          
> > > > > On Fri, Aug 27, 2010 at 06:33:35PM +0530, Dhananjay Goel wrote:
> > > > >
> > > > >            
> > > > > >      Yes, exactly. So, we wanted to know if it is possible to *share USB*
> > > > > >      across VMs.
> > > > > >
> > > > > >              
> > > > > I don't think USB protocol has been designed for *sharing*.
> > > > > I'm pretty certain only one computer/device/VM can use USB device at a
> > > > > time.
> > > > >
> > > > >            
> > > > This might work with firewire devices, I'm not sure.
> > > >
> > > >
> > > >          
> > > Yeah, firewire (iee1394) is designed to so that you can attach
> > > the devices to multiple computers..
> > >
> > > If you attach the same firewire-disk to multiple computers,
> > > and use the disk from multiple computers at the same time,
> > > you *will* corrupt the filesystem on the disk.
> > >
> > > Unless you run some kind of filesystem that has lock-manager,
> > > that can coordinate the shared access to the disk..
> > > ie. you must be running cluster-aware filesystem.
> > >
> > > -- Pasi
> > >
> > >
> > >        
> > Well guys, but we're talking about USB. The USB protocol is different
> > from firewire one. But that's right that I didn't know that. How is it
> > exactly done with the firewire to connect to multiple computers?
> >
> >      
> Some (or all?) firewire devices have 'daisy chain' connectors,
> so you can link multiple devices together..
>
> You can use those connectors to hook up the same device to multiple computers.
>
> People have implemented for example cheap proof-of-concept failover Oracle DB 
> clusters
> using firewire disks as cheap 'shared storage'.. there are many tutorials
> about that on the internet.
>
> -- Pasi
>
>    
Oh, great! Thanks for sharing this information!

Michal

--
Michal Novotny<minovotn@xxxxxxxxxx>, RHCE
Virtualization Team (xen userspace), Red Hat


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