From owner-freebsd-scsi@FreeBSD.ORG Tue Feb 8 21:49:57 2005 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 93E4E16A4CE; Tue, 8 Feb 2005 21:49:57 +0000 (GMT) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 042A943D41; Tue, 8 Feb 2005 21:49:57 +0000 (GMT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.13.1/8.13.1) id j18LnuHd090613; Tue, 8 Feb 2005 15:49:56 -0600 (CST) (envelope-from dan) Date: Tue, 8 Feb 2005 15:49:56 -0600 From: Dan Nelson To: Scott Long Message-ID: <20050208214956.GA3104@dan.emsphone.com> References: <4208F618.3000400@freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4208F618.3000400@freebsd.org> X-OS: FreeBSD 5.3-STABLE X-message-flag: Outlook Error User-Agent: Mutt/1.5.6i cc: freebsd-scsi@freebsd.org Subject: Re: how CAM/HBA probe for devices? X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Feb 2005 21:49:57 -0000 In the last episode (Feb 08), Scott Long said: > For iSCSI, this obviously won't work. CAM has no concept of iSCSI > addresses, and even if it did, doing a linear scan of even a small > subnet would be prohibitively expensive. What is really needed is a > new XPT layer that understands iSCSI. By this, I mean a layer that > understands how to properly scan and detect targets, how to log into > them, etc. It should also have a certain amount of flexibility so > that hardware-assisted solutions can plug in and pick-and-choose the > pieces they need from the transport layer. > > Lucent did an iSCSI initiator for FreeBSD 4.x a while back and I > think they got around all of this by telling CAM not to auto-scan at > boot, followed by having the driver announce devices to CAM directly > (look at the ATAPI-CAM code for an example of how to do this) and do > all the detection and login work behind CAM's back. This really > should only be considered a hack though. If you're interested, I > might be able to dig up the link to it. We never pursued integrating > it to the FreeBSD tree because of very restrictive licensing terms on > it. The fibre-channel drivers (isp,mpt) must have been the first to have hit this problem; do they do the same thing as atapicam? -- Dan Nelson dnelson@allantgroup.com