Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!gem.mps.ohio-state.edu!apple!vsi1!octopus!pete From: pete@Octopus.COM (Pete Holzmann) Newsgroups: comp.sys.ibm.pc Subject: Re: RLL controllers with MFM drives (exaggerated dangers...) Summary: Don't be so scared of it! Message-ID: <1989Oct23.152125.7013@Octopus.COM> Date: 23 Oct 89 15:21:25 GMT References: <2546@bingvaxu.cc.binghamton.edu> <4265@ncsuvx.ncsu.edu> <736@galen.acc.virginia.edu> <4275@ncsuvx.ncsu.edu> Reply-To: pete@octopus.COM (Pete Holzmann) Organization: Octopus Enterprises, Cupertino CA Lines: 77 In article <4275@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) writes: > As a professional, I would much rather overexaggerate the danger to >a slight degree than to underrate it. This I can agree with. But how much should we 'professionals' exaggerate the danger? In my rather extensive experience with using MFM "rated" drives under RLL, I can give you the following facts: (1) Old Seagate ST-225's (and the identical ST-238's) are not good under RLL. Don't try it! Supposedly, Rev 3 and up are better. I'm still not ready to waste my time on one. (2) Most, if not all (I've yet to see any hard facts that contradict my 'all' here...) MFM/RLL pairs are absolutely identical hardware. The only difference is that the ones sold with an RLL part number have been specifically tested for RLL and are guaranteed to work with an RLL format. ***What you get when you pay the extra bucks is a guarantee that RLL will work. You do not get different hardware!*** (3) The **only** drive that I have ever personally seen fail to work reliably with an RLL format is a Toshiba 56MB drive. And it *was* rated for RLL!!! (Note that I avoid ST-225 upgrades...) I've done a zillion Maxtors, ST-251's, and Micropolises. A few Miniscribes, a few Priams. Maxtor 1140's are especially nice, because a person can usually get a full 1224 cylinders out of them (i.e. treat it as a 2190) instead of the 'rated' 918. Yes, the extra cylinders are not under warranty, so you need to do a good job of pre-testing before using them; most customers are willing to take the time, in order to turn what is guaranteed as a 120MB drive, into a very nice 230MB drive! (4) The only drives I've heard of having any significant trouble are Seagate and Miniscribe. Does this mean they are lower quality? You judge for yourself! (5) This is not a 'short term' problem or solution. I've been doing this for a few years now, ever since RLL controllers became available. The format does not deteriorate any more than MFM formatting does. (6) Those who tell you that RLL requires more careful head positioning or media capable of higher storage densities are blowing smoke. They do not know what they are talking about. I don't have a copy any more, but I wrote a few extensive articles a year ago explaining how RLL works. Maybe somebody can send me a copy; I'll edit a few of the typos and repost. > There is a reason MFM drives are not RLL-rated: they were not >designed to meet RLL standards or performance. Period. Not true, except for earlier ST-225 drives. And the ST-238 labeled versions of those drives, even though 'rated' for RLL, were very unreliable in an RLL format. Those drives are what gave RLL a bad name. > Yes, you CAN get away with it. But your hard drive is living on >borrowed time. Some drives can hack it, most can't. Unky Dave, you've got to be careful with your wording. The *worst* that can happen is that your 'format is living on borrowed time'. RLL formatting *never* will do physical damage to a drive! > I think I'd rather see 20 people go short drive room than I would >see 1 person lose his papers/research project/thesis/whatever to a >hard drive pushed beyond its limits. I'd rather let all 20 decide for themselves, with full knowledge of the minimal risk involved. >unkydave@shumv1.ncsu.edu Pete -- Peter Holzmann, Octopus Enterprises |(if you're a techie Christian & are 19611 La Mar Ct., Cupertino, CA 95014 |interested in helping w/ the Great UUCP: {hpda,pyramid}!octopus!pete |Commission, email dsa-contact@octopus) DSA office ans mach=408/996-7746;Work (SLP) voice=408/985-7400,FAX=408/985-0859