From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:57446) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfC7R-0001zV-6Y for qemu-devel@nongnu.org; Wed, 22 May 2013 12:42:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UfC7O-0000wR-EA for qemu-devel@nongnu.org; Wed, 22 May 2013 12:42:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2219) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfC7O-0000wD-6c for qemu-devel@nongnu.org; Wed, 22 May 2013 12:42:26 -0400 Date: Wed, 22 May 2013 17:42:19 +0100 From: "Richard W.M. Jones" Message-ID: <20130522164219.GW4515@redhat.com> References: <20130516134415.GB9846@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [RFC] block-trace Low Level Command Supporting Disk Introspection List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wolfgang Richter Cc: Paolo Bonzini , qemu-devel , stefanha On Wed, May 22, 2013 at 11:51:16AM -0400, Wolfgang Richter wrote: > This is actually interesting. Does the QEMU nbd server support multiple > readers? Yes. qemu-nbd has a -e/--shared= option which appears to do exactly what it says in the man page. $ guestfish -N fs exit $ ls -lh test1.img -rw-rw-r--. 1 rjones rjones 100M May 22 17:37 test1.img $ qemu-nbd -e 3 -r -t test1.img >>From another shell: $ guestfish --format=raw -a nbd://localhost Welcome to guestfish, the guest filesystem shell for editing virtual machine filesystems and disk images. Type: 'help' for help on commands 'man' to read the manual 'quit' to quit the shell > run > list-filesystems /dev/sda1: ext2 Run up to two extra guestfish instances, with the same result. The fourth guestfish instance hangs at the 'run' command until one of the first three is told to exit. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top