Subject: Re: Integration of SCST in the mainstream Linux kernel
From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Vladislav Bolkhovitin <vst@vlnb.net>
Cc: Jeff Garzik <jeff@garzik.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Mike Christie <michaelc@cs.wisc.edu>, linux-scsi@vger.kernel.org,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       James Bottomley <James.Bottomley@HansenPartnership.com>,
       scst-devel@lists.sourceforge.net,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
       Julian Satran <Julian_Satran@il.ibm.com>
In-Reply-To: <1202258902.2220.102.camel@haakon2.linux-iscsi.org>
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Content-Type: text/plain
Date: Tue, 05 Feb 2008 16:51:28 -0800
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On Tue, 2008-02-05 at 16:48 -0800, Nicholas A. Bellinger wrote:
> On Tue, 2008-02-05 at 22:01 +0300, Vladislav Bolkhovitin wrote:
> > Jeff Garzik wrote:
> > > 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.
> > > 
> > > 
> > > AoE is truly a thing of beauty.  It has a two/three page RFC (say no more!).
> > > 
> > > But quite so...  AoE is limited to MTU size, which really hurts.  Can't 
> > > really do tagged queueing, etc.
> > > 
> > > 
> > > iSCSI is way, way too complicated. 
> > 
> > I fully agree. From one side, all that complexity is unavoidable for 
> > case of multiple connections per session, but for the regular case of 
> > one connection per session it must be a lot simpler.
> > 
> > And now think about iSER, which brings iSCSI on the whole new complexity 
> > level ;)
> 
> Actually, the iSER protocol wire protocol itself is quite simple,
> because it builds on iSCSI and IPS fundamentals, and because traditional
> iSCSI's recovery logic for CRC failures (and hence alot of
> acknowledgement sequence PDUs that go missing, etc) and the RDMA
> Capable
> Protocol (RCaP).

this should be:

.. and instead the RDMA Capacle Protocol (RCaP) provides the 32-bit or
greater data integrity.

--nab

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