From owner-freebsd-scsi Fri Apr 20 13: 7:53 2001 Delivered-To: freebsd-scsi@freebsd.org Received: from mail.wolves.k12.mo.us (mail.wolves.k12.mo.us [207.160.214.1]) by hub.freebsd.org (Postfix) with ESMTP id 26E0F37B422; Fri, 20 Apr 2001 13:07:50 -0700 (PDT) (envelope-from cdillon@wolves.k12.mo.us) Received: from mail.wolves.k12.mo.us (cdillon@mail.wolves.k12.mo.us [207.160.214.1]) by mail.wolves.k12.mo.us (8.9.3/8.9.3) with ESMTP id PAA87410; Fri, 20 Apr 2001 15:07:48 -0500 (CDT) (envelope-from cdillon@wolves.k12.mo.us) Date: Fri, 20 Apr 2001 15:07:47 -0500 (CDT) From: Chris Dillon To: Mike Smith Cc: Domas Mituzas , Subject: Re: mly driver does not work with SCA in up-to-date 4.3 In-Reply-To: <200104201938.f3KJcbf01621@mass.dis.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Fri, 20 Apr 2001, Mike Smith wrote: > > On Thu, 19 Apr 2001, Mike Smith wrote: > > > > > I *knew* that interfacing this driver to CAM was a bad idea, and I > > > was right. 8( > > > > I'm kinda glad you did, since when I had to pull the Mylex controller > > when I could no longer get the system to boot, I just hooked one of > > the disks from the RAID1 array onto a regular SCSI controller and > > never had to edit fstab since the device name never changed. Its only > > a minor advantage, I know. What is it about CAM that doesn't fit well > > with what you're doing? > > This, just for starters. 8) > > Basically, CAM insists that things behave exactly like SCSI disks, > etc. And RAID arrays just don't; the driver has to fake up all > sorts of rubbish like whether the array supports disconnect, > tagged queueing, its transfer rate, etc. I gather this would also cause problems for putting the ATA stuff under the CAM umbrella? I thought the idea behind CAM was to be somewhat generic in nature, not SCSI-specific. > I thought initially that because the array uses a subset of > SCSI-like commands, it'd make sense. Unfortunately, it doesn't > support enough of them to be useful. A wiser compromise would be > to have an optional CAM interface that can talk to non-disk > devices on the SCSI bus and just interface the disks directly to > the bio layer, as I used to do with other drivers. Would this help out the aforementioned ATA-under-CAM problems? -- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net FreeBSD: The fastest and most stable server OS on the planet. For IA32 and Alpha architectures. IA64, PPC, and ARM under development. http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message