Date: Fri, 14 Apr 1995 10:47:27 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: dufault@hda.com (Peter Dufault) Cc: freebsd-hackers@FreeBSD.org, freebsd-scsi@FreeBSD.org Subject: Re: SCSI target Message-ID: <199504141747.KAA01193@gndrsh.aac.dev.com> In-Reply-To: <199504141538.LAA00581@hda.com> from "Peter Dufault" at Apr 14, 95 11:38:55 am
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> > I've added a SCSI target device. Using this you can act as a target > and another system acting as an initiator can send data to you over > the SCSI bus. > > However, the only host adapter that supports this is the Adaptec > 1542B. The 1542C will hang the bus big time if you put it into > target mode, so I've locked it out. Great! But one of my 1542B's bit the dust about a month ago so now I only have one of them :-( :-(. > I have little hope that most of the commercial firmware will support > this properly, so if some of our firmware crankers want to start > cranking firmware they can look at the isa/aha1542c to get a feel > for how it should act. I'll have a Acculogic board with the NCR > 825 in house for a while. If you loose that card and still need one to work with I can arrange to put an NCR 53C810 controller in your house on a permanent loan basis. > Basically there is an escape added to put the host adapter in target > mode. Once it is in target mode it must respond to the mandatory > commands: INQUIRY, REQUEST SENSE, SEND DIAGNOSTIC and TEST UNIT > READY as well as the two data transfer commands SEND DATA and > RECEIVE DATA. > > The 1542 model is good, and I suggest we just use that as much as > possible. > > You can set up a data transfer in advance, with information that > indicates which initiator it is for, and then when that initiator > connects the board does the transfer. > > If an initiator connects to the 1542 when it doesn't have a transfer > set up for that initiator, the 1542 will disconnect, generate a > device interrupt, and report the ID and LUN of the initiator that > connected as well as the amount of data the initiator wants to > transfer. > > Eventually I'd like to add support for reserving units on the SCSI > bus, sharing read only disk partitions, and running TCP/IP over > SCSI using target mode capable host adapters. I think that could > make for a nice little cluster. Well, with 100MB/S ethernet support now being a reality TCP/IP over SCSI only has an advantage for *wide* scsi controllers. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Custom computers for FreeBSD
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