Date: Fri, 9 Apr 1999 23:20:48 -0800 (AKDT) From: Steve Howe <groggy@iname.com> To: Darryl Okahata <darrylo@sr.hp.com> Cc: freebsd-scsi@FreeBSD.ORG, freebsd-questions <questions@FreeBSD.ORG> Subject: Re: board not responding Message-ID: <Pine.BSF.3.96.990409224603.1844A-100000@en26.l1.net> In-Reply-To: <199904110500.WAA06462@mina.sr.hp.com>
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> > ahc0 <Adaptec 2940 Ultra SCSI adapter> rev 1 int a irq 10 on pci:0:10:0 > > ahc0: aic7800 Wide Channel, SCSI Id=7, 16 SCBs > > ahc0 waiting for scsi devices to settle > > (ahc0:0:0): "IBM DDRS-34560D DC1B" type 0 fixed SCSI 2 > > sd0(ahc0:0:0): Direct-Access 4357MB (8925000 512 byte sectors) > > ahc0: board is not responding > > (term) (auto) (term) > > IBM DDRS-34560 HD <-> 2940UW <-> Toshiba 6401B CD <-> HP 4020 CD/RW > > 68 pin 50 pin 50 pin sorry, i had the CD wrong ... i hear what you are saying, but don't know what it means. usually when i hear "single-ended", i think "as opposed to differential". the IBM spec sheets for the drive state: "Enable SCSI terminator SE 50/68 pin" which makes sense, since only the 2944 and 80 pin (AFAIK) adapters are differential units - which i think means that they have two-way communication paths to cut down on interference from electrical "echoes". but anyway - further testing shows the problem to be the Toshiba CDROM (40x). the IBM HD works fine alone, and works fine with the HP CD/RW. the boot floppy boots up. but when i add the Toshiba, with either the IBM or the HP in addition, the SCSI bus dies as shown above. i also notice that the Toshiba causes the Adaptec Bios (2.20) to take forever (3-4 minutes) to finish - when there is no CD in the CDROM. not so with the HP when it is empty. ------------------------------------ and as i write this - whala! i found the problem!!! but i'll send this off in case it helps anyone else; i didn't have too much luck scanning the handbook, faq, maillists, web ... and there are alot of good keywords in here ... it appears that the problem was the Adaptec BIOS speed settings for the CDROM. i had Sync-Negotiation DISABLED for the CDROMs, which gave them a speed of "20.0". when i lower it to 16.7, everything starts working fine! yippie! > The "IBM DDRS-34560D" is an LVD drive (I've got this exact drive, > with the same firmware rev). For this IBM LVD drive, what appears to be > the "term" jumper is really the jumper that controls LVD vs SE HVD > (single-ended HVD), and "enabling termination" really puts the drive > into single-ended mode. You also need an external terminator with this > drive (with all LVD drives, actually); there is no built-in termination > to enable or disable. it only forces SE mode on 80 pin connections - 50/68 is always SE ... with the exception of the 2944 ... STD disclaimer: "i believe" ... > As your diagram doesn't show an explicit external terminator with > the drive, that might be your problem: no termination. > > [ In my case, I ordered a "wide SCSI" drive, expecting an SE HVD drive. > I received an LVD drive, instead. While this is certainly a "wide > SCSI" drive, it was unexpected, as I had to scramble to find some > ribbon cable termination. I'm not really complaining, mind you; I'd > rather have an LVD drive than a plain SE HVD one, as it'll be much > easier for me to upgrade to an LVD controller, should I decide to do > so. ] thanks ;) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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