From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Novotny Subject: Re: Virtualization project idea Date: Fri, 27 Aug 2010 15:17:39 +0200 Message-ID: <4C77BAF3.2050609@redhat.com> References: <20100827084622.GA2804@reaktio.net> <20100827091928.GB2804@reaktio.net> <20100827105721.GD2804@reaktio.net> <20100827115449.GE2804@reaktio.net> <20100827125317.GF2804@reaktio.net> <20100827130847.GG2804@reaktio.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20100827130847.GG2804@reaktio.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: =?ISO-8859-1?Q?Pasi_K=E4rkk=E4inen?= Cc: Dhananjay Goel , James Harper , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 08/27/2010 03:08 PM, Pasi K=E4rkk=E4inen wrote: > On Fri, Aug 27, 2010 at 06:33:35PM +0530, Dhananjay Goel wrote: > =20 >> Yes, exactly. So, we wanted to know if it is possible to *share US= B* >> across VMs. >> >> =20 > 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 > > =20 Pasi, I agree. I think the think here is that Dhananjay confused the USB=20 device sharing with the file system sharing. I guess the USB protocol=20 was not designed for sharing nevertheless sharing the filesystem on a=20 USB stick is a completely different think. Dhananajay, you need to plug in the USB stick onto one computer (and=20 it's impossible to plug it into multiple computer at one time, of=20 course) and then setup the sharing. Everybody here is talking about the=20 hardware abstraction and virtualization and what you wrote is a=20 completely different thing - it's software-related and this has nothing=20 to do with the hardware emulation/abstraction what-so-ever. Considering the NFS and all the sharing protocols there was something=20 why it doesn't corrupt the data. I'm no expert on this subject but I=20 think this is because they run in the server-client mode. All the=20 clients are talking to the server and the server itself is one computer=20 that's having the just one operating system working with this particular=20 device - no matter what the underlaying device is - it may be everything=20 - USB stick, IDE/SCSI/SAS drive or just a relay workstation to save all=20 the data into one remote media (e.g. for replication). What I mean is=20 that the basic thing is that it's running on only one operating system=20 (because of it's connected to this one machine *only*) so it takes care=20 of everything and it's aware of the write-cache and data operations=20 being done to this media. Michal --=20 Michal Novotny, RHCE Virtualization Team (xen userspace), Red Hat