Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!mcdchg!ddsw1!karl From: karl@ddsw1.MCS.COM (Karl Denninger) Newsgroups: comp.sys.amiga Subject: Re: Seagate. Summary: Oh phooey. I do understand specs, and what RLL is and does. Do you? Message-ID: <3687@ddsw1.MCS.COM> Date: 5 Jul 89 21:25:11 GMT References: <8907020047.AA15716@lilac.berkeley.edu> <3671@ddsw1.MCS.COM> <10403@polya.Stanford.EDU> Reply-To: karl@ddsw1.MCS.COM (Karl Denninger) Organization: Macro Computer Solutions, Inc., Mundelein, IL Lines: 114 In article <10403@polya.Stanford.EDU> rokicki@polya.Stanford.EDU (Tomas G. Rokicki) writes: >In article <3671@ddsw1.MCS.COM>, karl@ddsw1.MCS.COM (Karl Denninger) writes: >> We've been using and selling Seagate drives for over three years. Here's >> our experiences with them: >> ST225 - Junk. But then again, what do you want for $200 or so? If you >> ST251/251N/277R - SOME models have problems. Older drives will get >> ST4038/4051 - Garbage. These were unreliable, often exhibiting >> ST4096/ST4144R - A good unit. We've had no undue problems with these. > >Fine, but then, he describes the machines within reach: > >> 3 ST251 - One running RLL which it's not rated for, but >> nonetheless works flawlessly! >> 1 ST4096 - Again, running RLL (and not rated for it) >> 1 ST4144R - RLL as well, and rated for it > >Boy, howdy, you just shot your credibility in my eyes to nothing with that. >Anyone who runs things out of spec---non-RLL drives RLL, 10MHz parts at >15MHz, etc., is just asking for trouble. And I will never go to such a >person for advice. Oh? That's your loss. We NEVER (repeat - NEVER) sell drives like this to customers. We DO use them like this in-house -- it's my own version of a torture test. I know darn well they may decide to lose format at any time, but note that they NEVER HAVE. Not in two and a half years. Our USENET partition is on one of those non-rated disks -- if it loses format, we lose spooled news. Big stinking deal. A few megs of unread news; or even your article that I just quoted! I'm worried sick :-) The RATED drives have important things on them. We may play with fire, but we're NOT stupid, and know what the fire can burn. If you knew as much about RLL and MFM encoding as you should, you would know that there is no way to damage a drive by running it RLL. The raw data rate does not change. No additional heat is produced. Only the encoding FORMAT is changed. Have you been listening to the Seagate babble ("RLL on a non-rated disk voids the warranty....") -- a marketing noise designed to sell disk drives at a higher price and profit margin? If you knew anything about Seagate drives, you would know that there is NO DIFFERENCE, PHYSICALLY OR ELECTRICALLY, between a RLL ST4144 and a Non-Rll ST4096. Or a ST251 and ST277R. Same drive, same electronics (logic board included). The only difference is in certification. If you get one that works RLL but isn't certified, it usually means that they needed more 4096's than 4144's, and didn't bother to CHECK the one you bought for conformance to the higher RLL specs. "Window margin" is the only, repeat, only spec which affects data recovery from an RLL device. If it's low enough (low enough jitter in the returned signal that is) then it will work. If not, it won't. Seagate is kind enough to print that spec on their final test sheet. We have, by using a nice analog disk test machine, come up with some ballpark figures which to date have predicted with 95%+ accuracy which drives will and won't work at the higher encoding density. I won't run a 16 Mhz CPU at 20 Mhz here or elsewhere - that generates more internal heat than the chip was designed for, and may shorten it's life. We don't sell MFM drives with RLL controllers to customers either - I don't like issuing RMA numbers, or having to explain why the disk lost it's format. But running a MFM drive at RLL density can't shorten it's life. It is RISK FREE when done in-house if you make nice daily backups and only put that which you are willing to lose on the disk. Besides, we have a few extra drives laying around -- why buy one new when you can pull one marked "engineering use only" off the shelf and run it until it craps out, at which time you repeat that process? Please explain why we have never lost data due to this practice if we don't know what we're doing...... >I will never buy a Seagate drive. I have seen many fail. I know for a fact >my data is worth more than a cheap drive. I paid $1000 for a CDC Wren and >$750 for a Quantum 80S---both excellent drives, neither of which I have >heard of or had any problems with. Other people, more financially strapped >than I, may take their chances. But talk to someone who does not run things >out of spec. Talk to someone who respects engineering, who understands why >things are spec'ed at all. That's ok. Last month I watched the DEC field service people pull a Quantum out of a Microvax (DEC private-labels Quantums as DEC RD53's at 500% markup) for replacement due to it deciding to eat the spindle bearings -- the drive was 9 months old. Impressive sounds were coming from that cabinet prior to it's death.... CDC has some nice products, but they are EXPENSIVE. Now that they have been bought by Seagate it remains to be seen what happens to the price AND quality of their products. (CDC's "MFM" units will, 99% of the time, run RLL as well without a hitch. They have excellent quality control. :-) I do respect engineering, but I also respect marketing. Marketing and production requirements drive Seagate, not necessarially engineering. Seagate simply doesn't test all the drives for RLL, and they only make ONE drive for both purposes. Talk to someone who knows what the difference is between RLL & MFM encoding; someone who knows how to determine whether or not what they are doing is going to work. Or, Gods forbid, try someone who knows what the manufacturer produces (dissecting crashed drives & checking part numbers against one another is informative). Talking to someone who blows smoke and spouts specs is counter-productive. Of course, if you never make backups you deserve what you get. In that case you better buy the best drive you can find -- and then pray to several Gods to protect you from Mr. & Mrs. Murphy. Guaranteed you'll need it. Finally, a repeat from my last post on this subject -- keep that disk drive COOL and you'll continue to use the same drive for a nice long time. -- Karl Denninger (karl@ddsw1.MCS.COM, !ddsw1!karl) Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910] Macro Computer Solutions, Inc. "Quality Solutions at a Fair Price"