From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:38382) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R4FIs-0003rQ-AX for qemu-devel@nongnu.org; Thu, 15 Sep 2011 13:00:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1R4FIq-0007Lv-LT for qemu-devel@nongnu.org; Thu, 15 Sep 2011 13:00:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:14504) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R4FIq-0007Lr-Ak for qemu-devel@nongnu.org; Thu, 15 Sep 2011 13:00:44 -0400 From: Orit Wasserman Date: Thu, 15 Sep 2011 19:59:44 +0300 In-Reply-To: <4E71F67B.3@redhat.com> References: <1315628610-28222-1-git-send-email-ronniesahlberg@gmail.com> <1315628610-28222-2-git-send-email-ronniesahlberg@gmail.com> <20110912091408.GA3465@stefanha-thinkpad.localdomain> <4E71956B.6030902@redhat.com> <4E71BBE3.5000207@redhat.com> <4E71C146.6070406@redhat.com> <4E71E4B2.9060304@redhat.com> <4E71E854.10302@redhat.com> <1316090109.29180.43.camel@dhcp-1-120.tlv.redhat.com> <4E71F67B.3@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Message-ID: <1316105991.29180.51.camel@dhcp-1-120.tlv.redhat.com> Mime-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] This patch adds a new block driver : iSCSI List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: kwolf@redhat.com, Stefan Hajnoczi , dlaor@redhat.com, qemu-devel@nongnu.org, fujita.tomonori@lab.ntt.co.jp, Ronnie Sahlberg , hch@lst.de On Thu, 2011-09-15 at 14:58 +0200, Paolo Bonzini wrote: > On 09/15/2011 02:34 PM, Orit Wasserman wrote: > >> > Then you need an iSCSI*target* that understands qcow2, like qemu-nbd > >> > but for iSCSI... that's exactly the thing you were worried about > >> > implementing. > > > > Not really , this is just part of the target configuration. > > For each file in the chain we create a lun in the target that is backed > > by the file and we number the luns in chronological order (base is lun > > 1) . you can look at a tgtd configuration here > > http://wiki.qemu.org/Features/LiveBlockMigration#Example_single_base_master_image. > > That's surely a weird way to use iSCSI. :) :) > It's clever, but I would call that shared storage, since you need to > share the details of the snapshot chain between the source and > destination, down to the file names. We need a more precise nomenclature. We store the parent base image inside the image (relative path). We can reverse engineer it in the destination , start at the highest lun ,read it's parent name , create a symbolic link to the parent (previous lun) and so on ... Orit > Paolo