From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH RFC 1/3] add fc transport events Date: Mon, 14 Jun 2004 12:15:03 +1000 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <40CD0A27.5070504@torque.net> References: <40B597F5.2030501@cs.wisc.edu> <1087088793.1730.19.camel@mulgrave> <40CCBCCA.1040302@us.ibm.com> <1087166778.10940.23.camel@mulgrave> Reply-To: dougg@torque.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from bunyip.cc.uq.edu.au ([130.102.2.1]:25096 "EHLO bunyip.cc.uq.edu.au") by vger.kernel.org with ESMTP id S261685AbUFNCPU (ORCPT ); Sun, 13 Jun 2004 22:15:20 -0400 In-Reply-To: <1087166778.10940.23.camel@mulgrave> List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Mike Christie , SCSI Mailing List James Bottomley wrote: > On Sun, 2004-06-13 at 16:44, Mike Christie wrote: > >>I am not adding a host and a device transport class. I am structuring >>things so there is a single fc transport class. > > > I don't think that's such a good idea. A class is supposed to represent > an interface on a device. The host and scsi device should have separate > interfaces. The only reason we don't have any host interfaces in the > transport classes is because no-one has yet had a reason to add one. > However, since the loop status is definitely a host property, you > do...part of what's missing is an attribute showing the loop state. SPI > has a similar need; the host property there is LVD or SE, and we might > be interested in transitions between them. There are 4 categories of "devices" that we might try to address: a) host (PCI side and SCSI transport side) b) transport service delivery subsystem c) target device server d) logical unit Only a, b + c are associated with the transport in question. In category b could be FC switches and SAS expanders. In category d could be sATA, SPI or SAS disks behind a FC target. So the logical unit doesn't necessarily belong to the same transport as the initiator (especially in iSCSI) as noted above by James. So the end point of the transport is category c and according to SPC-3 a target device server is addressed via "well known" logical units (see section 8). [The standard requirement for a device server to respond to lun==0 for INQUIRY and REPORT LUNS is a related hack that allows a SCSI disk to double as a target device server and a lu.] Is our transport class design flexible enough for this level of complexity? Doug Gilbert