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Re: [Xen-devel] Virtualization project idea

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 
using firewire disks as cheap 'shared storage'.. there are many tutorials
about that on the internet.

-- Pasi

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