From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Scott M. Ferris" Subject: Re: [linux-iscsi-devel] Re: [PATCH RFC] replace ioctl for sysfs take 2 Date: Tue, 7 Sep 2004 16:05:20 -0500 (CDT) Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20040907210520.0251476C56@isis.visi.com> References: <1094589763.2401.143.camel@mulgrave> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from conn.mc.mpls.visi.com ([208.42.156.2]:4077 "EHLO conn.mc.mpls.visi.com") by vger.kernel.org with ESMTP id S268655AbUIGVFW (ORCPT ); Tue, 7 Sep 2004 17:05:22 -0400 In-Reply-To: <1094589763.2401.143.camel@mulgrave> from James Bottomley at "Sep 7, 2004 04:42:40 pm" List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: "Scott M. Ferris" , Mike Christie , Mike Christie , Matthew Wilcox , Christoph Hellwig , iscsi -devel , David Wysochanski , "Surekha.PC" , SCSI Mailing List James Bottomley wrote: > On Tue, 2004-09-07 at 15:19, Scott M. Ferris wrote: > > > That's not a very helpful analogy, since only SPI and FC-AL resemble a > > bus, and all of the newer SCSI transports are switched fabrics. > > Well, I'm at a bit of a loss to make it plainer ... a host is somewhere > you plug your bus this is an obvious concept even for switched > fabrics. So a host is where you plug your (non-existent) bus? I think it would be clearer to use terminology from SAM. > > > In iSCSI that's really the other end point. Using abstractions > > > incorrectly (like a single host for the entire iSCSI system) is > > > bound to end up with problems due to the concept mismatch. > > > > I have trouble understanding your viewpoint. Your answers to the > > following questions will hopefully clear things up. > > I doubt it, but I'll try. Thanks. > > Do you think Linux hosts should be used in a similar way by all > > switched SCSI transports (e.g. FC-SW, iSCSI, SAS)? If not, why not? > > Yes. I'm glad we agree on that. > > Do you think switched SCSI transports should allocate one Linux host > > for each I_T nexus? > > No. This is exactly why I ask these questions. The iSCSI driver developers just implemented this, because they thought this is what you and Christoph were asking for. Apparently it's not what you wanted. > > > Do you think switched SCSI transports should allocate one Linux host > > for each (SAM-2 or SAM-3) SCSI initiator port? > > Yes. Thank you. This is a much clear statement of your intent. > > Do you think switched SCSI transports should allocate one Linux host > > for each (SAM-2 or SAM-3) SCSI initiator device? > > No. Should all drivers that currently use one host for each SCSI initiator device, and a channel for each initiator port on each device, be modified to use a host for each initiator port? Documentation/scsi/scsi_mid_low_api.txt says that a host corresponds to a SCSI initiator device. Could someone change that to say SCSI initiator port instead, since that seems to be the new goal? -- Scott M. Ferris, sferris@acm.org