Date: Thu, 30 Mar 1995 09:53:31 -0500 (EST) From: John Capo <jc@irbs.com> To: olsenc@ichips.intel.com Cc: freebsd-hardware@freefall.cdrom.com Subject: Re: Questions about NCR PCI SCSI driver Message-ID: <199503301453.JAA02109@irbs.com> In-Reply-To: <9503291840.AA50731@dtt030.intel.com> from "olsenc@ichips.intel.com" at Mar 29, 95 10:40:43 am
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olsenc@ichips.intel.com writes: > > Hello: > > I asked this before. It seems as though I have to ask each question twice > to get an answer from this group. > > Will performing certain SCSI operations in FreeBSD (say tape rewind) cause the > SCSI bus to hang until completion? People have complained about this in > Linux because the driver is not polished. Hopefully, someone who uses this > device can testify that things are working ok or not. > A target will release the bus during execution of a command if the initiator has granted the target permission to disconnect and the target chooses to disconnect. The target is in control of the opertion and can not be forced to disconnect from the bus. Most all modern SCSI targets will disconnect, if allowed to, even when it would be more efficient and faster for them not to disconnect. I have used several SCSI tape drives with 1542-[ABC] controllers and the all released the bus as expected. I am sure the NCR driver behaves the same way. I say most modern SCSI devices because one of my real world projects is a multi-channel digital audio recorder. This embedded system has dual SCSI busses with multiple initiators and targets. My client was approached by a company that wanted to produce a custom RAID unit for them, an agreement was struck and the RAID unit was delivered. It _DID NOT DISCONNECT_. Needless to say, it was not accepted. BTW, this project uses a MC68340 CPU and FreeBSD is the cross-development environment. John Capo
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