From owner-freebsd-scsi Fri Apr 20 12:37:19 2001 Delivered-To: freebsd-scsi@freebsd.org Received: from mass.dis.org (mass.dis.org [216.240.45.41]) by hub.freebsd.org (Postfix) with ESMTP id DC52637B43C for ; Fri, 20 Apr 2001 12:37:16 -0700 (PDT) (envelope-from msmith@mass.dis.org) Received: from mass.dis.org (msmith@localhost [127.0.0.1]) by mass.dis.org (8.11.2/8.11.2) with ESMTP id f3KJcbf01621; Fri, 20 Apr 2001 12:38:38 -0700 (PDT) (envelope-from msmith@mass.dis.org) Message-Id: <200104201938.f3KJcbf01621@mass.dis.org> X-Mailer: exmh version 2.1.1 10/15/1999 To: Chris Dillon Cc: Domas Mituzas , scsi@FreeBSD.ORG Subject: Re: mly driver does not work with SCA in up-to-date 4.3 In-reply-to: Your message of "Fri, 20 Apr 2001 11:25:13 CDT." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 20 Apr 2001 12:38:37 -0700 From: Mike Smith Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > 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 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. -- ... every activity meets with opposition, everyone who acts has his rivals and unfortunately opponents also. But not because people want to be opponents, rather because the tasks and relationships force people to take different points of view. [Dr. Fritz Todt] V I C T O R Y N O T V E N G E A N C E To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message