From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: Integration of SCST in the mainstream Linux kernel Date: Mon, 04 Feb 2008 17:00:33 -0600 Message-ID: <1202166033.3096.141.camel@localhost.localdomain> References: <1201639331.3069.58.camel@localhost.localdomain> <47A05CBD.5050803@vlnb.net> <47A7049A.9000105@vlnb.net> <1202139015.3096.5.camel@localhost.localdomain> <47A73C86.3060604@vlnb.net> <1202144767.3096.38.camel@localhost.localdomain> <47A7488B.4080000@vlnb.net> <1202145901.3096.49.camel@localhost.localdomain> <1202151989.11265.576.camel@haakon2.linux-iscsi.org> <20080204224314.113afe7b@core> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from accolon.hansenpartnership.com ([76.243.235.52]:48660 "EHLO accolon.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757265AbYBDXAl (ORCPT ); Mon, 4 Feb 2008 18:00:41 -0500 In-Reply-To: <20080204224314.113afe7b@core> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Alan Cox Cc: Linus Torvalds , "Nicholas A. Bellinger" , Vladislav Bolkhovitin , Bart Van Assche , Andrew Morton , FUJITA Tomonori , linux-scsi@vger.kernel.org, scst-devel@lists.sourceforge.net, Linux Kernel Mailing List , Mike Christie On Mon, 2008-02-04 at 22:43 +0000, Alan Cox wrote: > > better. So for example, I personally suspect that ATA-over-ethernet is way > > better than some crazy SCSI-over-TCP crap, but I'm biased for simple and > > low-level, and against those crazy SCSI people to begin with. > > Current ATAoE isn't. It can't support NCQ. A variant that did NCQ and IP > would probably trash iSCSI for latency if nothing else. Actually, there's also FCoE now ... which is essentially SCSI encapsulated in Fibre Channel Protocols (FCP) running over ethernet with Jumbo frames. It does the standard SCSI TCQ, so should answer all the latency pieces. Intel even has an implementation: http://www.open-fcoe.org/ I tend to prefer the low levels as well. The whole disadvantage for IP as regards iSCSI was the layers of protocols on top of it for addressing, authenticating, encrypting and finding any iSCSI device anywhere in the connected universe. I tend to see loss of routing from operating at the MAC level to be a nicely justifiable tradeoff (most storage networks tend to be hubbed or switched anyway). Plus an ethernet MAC with jumbo frames is a large framed nearly lossless medium, which is practically what FCP is expecting. If you really have to connect large remote sites ... well that's what tunnelling bridges are for. James