On Friday 11 October 2002 12:34, Bernhard Beck wrote: >FWIW: We had similar symptoms happening here with an external HP > DLT1 drive off a motherboard-internal Adaptec Ultra2Wide > controller. The tape was running U2W in single-ended mode and was > connected using the HP provided LVD/SE cable. It appears the SCSI > bus was too long with that cable. After switching to a shorter > external cable (only about 30cm instead of 150cm) all SCSI > problems/tape errors disappeared. > >Bernhard
That would be pretty prima-faci evidence to me of a boogered termination someplace. The max length spec for the LVD cabling is ISTR several times longer than for std single-ended cableing, which is by itself about 40 meters! By going down to a 30cm cable, the echos are now so close that the circuitry isn't fast enough and doesn't see them. One other effect that I've no experience with might be that the LDV/SE cable might be one of the newer miniature cabling styles, resembling the very finely spaced ata100 cables. Its characteristic impedance is an unknown to me, whereas the regular, much wider cable is about 120 ohms. I'd think the smaller cables characteristic impedance might be a bit lower unless the wire size shrank in unison with the square laws involved in calculating impedances. And thats a huge guage shrink... Not practical to do in an IDC assembly style IMO. > >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED]]On Behalf Of Joshua >> Baker-LePain Sent: Friday, October 11, 2002 5:04 AM >> To: Jerry >> Cc: [EMAIL PROTECTED] >> Subject: Re: tape errors >> >> >> On Thu, 10 Oct 2002 at 5:30pm, Jerry wrote >> >> > Solaris >> > Exabyte EZ17 Autoloader w/m2 drive >> > 225m AME self clean tapes >> > Using dump.... >> > >> > Once it's busted can't even tar to the tape, either >> > gets stuck in the middle or just starts freaking out >> > and sounds like the tape is lost seeking around. >> > >> > As far as syslog, I got a bunch of scsi errors but >> > it's hard to decipher which ones were related since it >> > ended up powering off the drive and on to stop it from >> > resetting and clanking the tape back and forth. The >> > drive has never really been used and the tapes >> > shouldn't be that old, considering the admin before me >> > never even got it to control the changer. >> >> All I can say is, ouch. As others have said, start taking a >> good look at your hardware -- the changer, the cables, >> termination, the HBA... >> >> This sounds like a multi-goat problem. >> >> -- >> Joshua Baker-LePain >> Department of Biomedical Engineering >> Duke University -- Cheers, Gene AMD K6-III@500mhz 320M Athlon1600XP@1400mhz 512M 99.17% setiathome rank, not too shabby for a WV hillbilly
