This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Virtualization project idea

To: Pasi Kärkkäinen <pasik@xxxxxx>
Subject: Re: [Xen-devel] Virtualization project idea
From: Michal Novotny <minovotn@xxxxxxxxxx>
Date: Fri, 27 Aug 2010 15:17:39 +0200
Cc: Dhananjay Goel <dhananjaygoel123@xxxxxxxxx>, James Harper <james.harper@xxxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Fri, 27 Aug 2010 06:21:15 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <20100827130847.GG2804@xxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <20100827084622.GA2804@xxxxxxxxxxx> <AANLkTikKrUfikDogvD78K4A+STZ+SoGx_vEp7R+auG9J@xxxxxxxxxxxxxx> <20100827091928.GB2804@xxxxxxxxxxx> <AANLkTikSNL=t01VcKxubFSKADjjnoEeqr6TdbsRpLBUn@xxxxxxxxxxxxxx> <20100827105721.GD2804@xxxxxxxxxxx> <AANLkTinHmi=87ZiTbJFVHyJLau3uO1ER6yyN=2B4KKo-@xxxxxxxxxxxxxx> <20100827115449.GE2804@xxxxxxxxxxx> <AANLkTinUbCBwjJ17=8n9z8OwEUh8+oea_+-EYEVv1xA3@xxxxxxxxxxxxxx> <20100827125317.GF2804@xxxxxxxxxxx> <AANLkTikke8p3+m9C_npP87VVJA5czya2ie-xyFNC5pgx@xxxxxxxxxxxxxx> <20100827130847.GG2804@xxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20100430 Fedora/3.0.4-3.fc13 Thunderbird/3.0.4
On 08/27/2010 03:08 PM, 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.

-- Pasi

Pasi, I agree. I think the think here is that Dhananjay confused the USB device sharing with the file system sharing. I guess the USB protocol was not designed for sharing nevertheless sharing the filesystem on a USB stick is a completely different think.

Dhananajay, you need to plug in the USB stick onto one computer (and it's impossible to plug it into multiple computer at one time, of course) and then setup the sharing. Everybody here is talking about the hardware abstraction and virtualization and what you wrote is a completely different thing - it's software-related and this has nothing to do with the hardware emulation/abstraction what-so-ever.

Considering the NFS and all the sharing protocols there was something why it doesn't corrupt the data. I'm no expert on this subject but I think this is because they run in the server-client mode. All the clients are talking to the server and the server itself is one computer that's having the just one operating system working with this particular device - no matter what the underlaying device is - it may be everything - USB stick, IDE/SCSI/SAS drive or just a relay workstation to save all the data into one remote media (e.g. for replication). What I mean is that the basic thing is that it's running on only one operating system (because of it's connected to this one machine *only*) so it takes care of everything and it's aware of the write-cache and data operations being done to this media.


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

Xen-devel mailing list