Date: Thu, 31 Aug 1995 18:58:38 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: gibbs@freefall.FreeBSD.org (Justin T. Gibbs) Cc: FreeBSD-hackers@freebsd.org Subject: Re: 4GB Drives Message-ID: <199509010158.SAA13422@gndrsh.aac.dev.com> In-Reply-To: <199509010057.RAA03740@freefall.FreeBSD.org> from "Justin T. Gibbs" at Aug 31, 95 05:57:02 pm
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> > >> Hmm. Are you sure that the drive will not disconnect even for a short time > >> after receiving its command? > > > >Darn sure, I effectivly disabled disconnect/reconnect by tweaking the > >buffer full/empty ratios and a few other parameters in mode page 2. > > Why not just turn off disconnections in SCSI-Select? :) Because I can't do that on an NCR 53C825 :-). > >> >The data I need is being very difficult to obtain without spending major > >> >dollars on a scsi bus analyzer and a large logic analyzer :-(. I guess > >> >I could go out to the labs some weekend, but it is a pain to check in this > >> >much equipment. > >> > >> I would think that a scope attached to the led line would be sufficient > >> for most of the timing. > > > >Yes, it should be, but if I have things like command queueing occuring I > >can not correlate the edge created in the stripe layer with the edge > >created by the LED, it may be skewed by 1 cycle. Or I could go get a > >$10k storage scope and use single events :-). > > You will need to pause the sequencer in order to change the status > of the led anyway if you do it from the kernel, so the edges should > be distinguishable between kernel blinks and sequencer blinks. I well be blinking the controller LED from the sequencer, not the kernel, I have lots of blinking signals from the kernel, I have 8 x 16 bits worth of them if I so desire :-). -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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