From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Nicholas A. Bellinger" Subject: Re: Integration of SCST in the mainstream Linux kernel Date: Mon, 04 Feb 2008 14:59:40 -0800 Message-ID: <1202165980.11265.653.camel@haakon2.linux-iscsi.org> 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 smtp113.sbc.mail.mud.yahoo.com ([68.142.198.212]:31942 "HELO smtp113.sbc.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754570AbYBDXAO (ORCPT ); Mon, 4 Feb 2008 18:00:14 -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 , James Bottomley , 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 , Julian Satran 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. > In the previous iSCSI vs. FCoE points (here is the link again): http://www.ietf.org/mail-archive/web/ips/current/msg02325.html the latency discussion is the one bit that is not mentioned. I always assumed that back then (as with today) the biggest issue was getting ethernet hardware, espically switching equipment down to the sub millisecond latency, and on par with what you would expect from 'real RDMA' hardware. In lowest of the low, say sub 10 ns latency, which is apparently possible with point to point on high-end 10 Gb/sec adapters today, it would be really interesting to know how much more latency would be expected between software iSCSI vs. *oE when we work our way back up the networking stack. Julo, do you have any idea on this..? --nab > > Alan >