Date: Fri, 20 Apr 2001 15:07:47 -0500 (CDT) From: Chris Dillon <cdillon@wolves.k12.mo.us> To: Mike Smith <msmith@FreeBSD.ORG> Cc: Domas Mituzas <midom@delfi.lt>, <scsi@FreeBSD.ORG> Subject: Re: mly driver does not work with SCA in up-to-date 4.3 Message-ID: <Pine.BSF.4.32.0104201443390.86778-100000@mail.wolves.k12.mo.us> In-Reply-To: <200104201938.f3KJcbf01621@mass.dis.org>
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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
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