From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49494) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R47cz-0006U5-Ka for qemu-devel@nongnu.org; Thu, 15 Sep 2011 04:49:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1R47cy-0004K5-6R for qemu-devel@nongnu.org; Thu, 15 Sep 2011 04:49:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:18999) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R47cx-0004Jl-VT for qemu-devel@nongnu.org; Thu, 15 Sep 2011 04:49:00 -0400 Message-ID: <4E71BBE3.5000207@redhat.com> Date: Thu, 15 Sep 2011 11:48:35 +0300 From: Dor Laor MIME-Version: 1.0 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> In-Reply-To: <4E71956B.6030902@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] This patch adds a new block driver : iSCSI Reply-To: dlaor@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: kwolf@redhat.com, fujita.tomonori@lab.ntt.co.jp, qemu-devel@nongnu.org, Stefan Hajnoczi , hch@lst.de On 09/15/2011 09:04 AM, Paolo Bonzini wrote: > On 09/15/2011 01:08 AM, ronnie sahlberg wrote: >> I think it is reasonable to just not support iscsi at all for >> blocksize that is not multiple of 512 bytes >> since a read-modify-write cycle across a network would probably be >> prohibitively expensive. > > Agreed. > >> .bdrv_flush() I can easily add a synchronous implementation of this >> unless your patch is expected to be merged >> in the near future. > > We need the same patch for NBD, so I wouldn't bother with the > synchronous flush. > > Paolo > > It seems to me that using a qemu external initiator/target pairs like Orit's original design in http://wiki.qemu.org/Features/LiveBlockMigration#ISCSI_for_non_shared_storage would be a simpler (in terms of qemu code..) and flexible solution. I agree that embedding the iscsi initiation in qemu can simplify the end user life but since this scenario is expected to be used by higher level software it's not relevant here. The risk is to have to maintain more code that won't be as general as the tgtd/lio solutions out there.