Date: Tue, 13 Nov 2001 21:32:03 -0800 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Rick Hamell" <hamellr@heorot.1nova.com>, "Joshua" <joshua@submatrix.com> Cc: "FreeBSD-newbies" <freebsd-newbies@FreeBSD.ORG> Subject: RE: 40 and 80 pin cable and UDMA errors Message-ID: <000e01c16ccd$b1256d00$1401a8c0@tedm.placo.com> In-Reply-To: <Pine.BSF.4.21.0111131749300.20784-100000@heorot.1nova.com>
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>-----Original Message----- >From: owner-freebsd-newbies@FreeBSD.ORG >[mailto:owner-freebsd-newbies@FreeBSD.ORG]On Behalf Of Rick Hamell >Sent: Tuesday, November 13, 2001 5:53 PM >To: Joshua >Cc: FreeBSD-newbies >Subject: Re: 40 and 80 pin cable and UDMA errors > > > >> Been running it for a year, and have done six of my friends cables and no >> problems. Even have my raid set up like that. All my benchmarks show >> little to no slow down and the little it does show isnt worth what the >> computer looks likes or how the cooling is affected with out >rounded cables. > > Then you have been lucky. :) Granted with the stronger materials >used now in the wires, they're able to withstand it more. SCSI 68 and 80 >pin is still susceptiable to it these days though Let me put in my $0.02 cents here.. I've rolled my own SCSI cables for years - the ones they sell don't generally have enough connectors and not in the right places for the systems I've done. In my experience, I've never seen a failure on a ribbon cable caused by creases or bends or any such. Now, granted, if you repeatedly bend a cable back and forth over and over and over along one axis you will eventually break it. But copper is much more flexible than steel is and it streches too so those little wires are fairly well protected and resistant to this. However, what I have seen many times and has repeatedly dogged me is bad connectors. Sometimes it's the back of the connector where the cable is crimped in. Sometimes the failure is inside of the connector where it plugs onto the pins sticking out. The original 50 pin rectangular SCSI connectors and the smaller IDE connectors had lots of problems with their little square pins and bad contacts where the pin went into the connector. This is why when they redesigned those connectors for wide SCSI they made the pins more flattish, it lets you increase pressure on the pin. But the smaller form factor makes it even easier to bend pins if the connector isn't inserted exactly straight and almost impossible to bend them back without snapping them off. Also the crimps in the backs are even worse sources of trouble. Pulling cables out of the back of the drives by pulling on the cable and not the connector is a big contributor, unfortunately with the original SCSI and IDE connectors there wasn't anything on the connector to grab, so you had to pull it by the cable. I have SCSI cables in my junk pile that look _perfect_ but will give data errors when plugged in, and I've fixed many by cutting off the connector and recrimping a new one on, of course you can't do this when the connector is in the _middle_ of the cable. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-newbies" in the body of the message
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