From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Novotny Subject: Re: Virtualization project idea Date: Fri, 27 Aug 2010 15:47:29 +0200 Message-ID: <4C77C1F1.7090807@redhat.com> References: <20100827091928.GB2804@reaktio.net> <20100827105721.GD2804@reaktio.net> <20100827115449.GE2804@reaktio.net> <20100827125317.GF2804@reaktio.net> <20100827130847.GG2804@reaktio.net> <4C77BAF3.2050609@redhat.com> <20100827133042.GI2804@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: <20100827133042.GI2804@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 03:30 PM, Pasi K=E4rkk=E4inen wrote: > On Fri, Aug 27, 2010 at 03:17:39PM +0200, Michal Novotny wrote: > =20 >> On 08/27/2010 03:08 PM, Pasi K=E4rkk=E4inen wrote: >> =20 >>> 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= USB* >>>> 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 U= SB >> 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 th= e >> hardware abstraction and virtualization and what you wrote is a >> completely different thing - it's software-related and this has nothin= g >> 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 compute= r >> that's having the just one operating system working with this particul= ar >> device - no matter what the underlaying device is - it may be everythi= ng >> - USB stick, IDE/SCSI/SAS drive or just a relay workstation to save al= l >> 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 car= e >> of everything and it's aware of the write-cache and data operations >> being done to this media. >> >> =20 > Yep. > > If you want to share files from the hypervisor-host (from USB stick or = from actual disk) > to the VMs you *can* do it today over-the-network (nfs,cifs,webdav,ftp)= using the standard > client-server tools that have been used for over 20 years. > > If you don't want to do it over-the-network, but somehow 'through' the = hypervisor, > then you'd need to build some kind of special filesystem protocol that = is able > to do the client-server communication over the hypervisor specific path= s (xenbus etc). > And have drivers for it in the hypervisor-host, and in the VMs. > > -- Pasi > > =20 Ok Pasi, I know what you mean. I was talking about physical machines=20 since Dhananjay compared this to physical machines. I know sharing=20 between VMs is possible using specific paths like the xenbus one. Michal --=20 Michal Novotny, RHCE Virtualization Team (xen userspace), Red Hat