Date: Mon, 21 Feb 2000 23:39:13 -0800 From: Mike Smith <msmith@freebsd.org> To: "Kenneth D. Merry" <ken@kdm.org> Cc: Nanda Kumar <nanda@procsys.com>, freebsd-scsi@FreeBSD.ORG Subject: Re: Help to write a SCSI block driver Message-ID: <200002220739.XAA08488@mass.cdrom.com> In-Reply-To: Your message of "Mon, 21 Feb 2000 23:52:53 MST." <20000221235253.A16855@panzer.kdm.org>
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> On Tue, Feb 22, 2000 at 11:56:17 +0530, Nanda Kumar wrote: > > > > I have to write a SCSI block device driver for one RAID controller we > > have designed. Can anyone tell me how to go about it ? We have already > > one Windows miniport driver working for the same card. Please tell me a > > good sample driver to go through and if any document is available > > regarding how to write a SCSI block device driver and how it interacts > > with the system. I am quite new to the unix world. > > Well, the device model you use will really depend on what sort of interface > your RAID controller presents. > > There are two basic categories that other RAID controllers fall into right > now: > > - controllers that can function as a standard SCSI controller, as well as > a RAID controller. (e.g. you could put a CDROM drive on the controller, > and access it with standard SCSI commands) The DPT cards fall into this > category. > > - controllers that function primarily as a RAID controller, and don't > allow direct SCSI acess to devices on their busses. The AMI, Mylex, and > Compaq SmartRAID controllers fall into this category. This is not actually correct; all of these adapters have SCSI passthrough interfaces (except perhaps the Compaq controller, which I haven't looked at that closely). However, excluding the DPT (which I am not familiar with), none of these controllers present an interface which looks anything at all like a SCSI disk between a managed array and the system, and thus it's not appropriate to use CAM and the 'da' driver to talk to them. The Mylex driver, at least, will be growing a CAM passthrough for non-disk devices at some point in time. -- \\ Give a man a fish, and you feed him for a day. \\ Mike Smith \\ Tell him he should learn how to fish himself, \\ msmith@freebsd.org \\ and he'll hate you for a lifetime. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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