Date: Mon, 30 Mar 1998 11:46:42 -0700 From: "Justin T. Gibbs" <gibbs@plutotech.com> To: Matthew Jacob <mjacob@feral.com> Cc: "Justin T. Gibbs" <gibbs@plutotech.com>, Wilko Bulte <wilko@yedi.iaf.nl>, scsi@FreeBSD.ORG Subject: Re: SDT-7000 and other DDS-2 tapes Message-ID: <199803301850.LAA12168@pluto.plutotech.com> In-Reply-To: Your message of "Mon, 30 Mar 1998 10:41:46 PST." <351FE76A.5778EA38@feral.com>
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>Only attempt this if the tape is being read. Even then, it's >iffy. It depends really on whether, during reset conditions, you >can really believe the tape in the drive is the same one you >had. As CAM gives you an async notification when a bus reset occurs, you do know that the upcoming UA is for a bus reset, not a power on or media change event. >My take is that this is not something that the driver >layer should do. This is something that a higher level should >ascertain, since only it has knowledge of the information >encoding. I don't understand why the encoding is relevant. The tape peripheral, at least in CAM, can guarantee transaction ordering to the device even across an error condition. Regardless of the information encoding if the sequence of filemarks and blocks laid out on the tape match that of the requesting program (or in the case of reads, the returned data exactly matches what was written on the tape), there can be no confusion. >I would strenuosly argue that it'd better to figure >out a much more robust error return mechanism (something a la > > r/w -> EIO (error state latches) > > -> MTIOCGETERR, releases latch returns > error associated with EIO > | -> rw, error message to console, releases latch I believe that SGI has something like this that allows you to pull the last position, EOF, EOT, EOM flags, etc. I don't recall what they call it though. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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