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Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!uwvax!oddjob!ncar!ames!killer!chasm
From: chasm@killer.UUCP (Charles Marslett)
Newsgroups: comp.sys.ibm.pc,comp.sys.misc
Subject: Re: Disk Controller Question ?
Summary: Real stuff is bad enough
Message-ID: <4080@killer.UUCP>
Date: 13 May 88 18:15:26 GMT
References: <1255@kodak.UUCP> <638@mccc.UUCP>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 45

In article <638@mccc.UUCP>, pjh@mccc.UUCP (Pete Holsberg) writes:
> In article <1255@kodak.UUCP> crassi@kodak.UUCP (charlie crassi) writes:
> ...I need some help in answering a question about the RLL controllers !!
> ...
> ...I was told that the RLL controller will work fo about a month and then     
> ...will destroy the media which is not coated thick enough. Is there any
> ...truth to the matter. . .

> Your data is living on borrowed time!  Any medium which is not certified
> for RLL will eventually fail (unless you are VERY lucky!) because of the
> demands an RLL controller makes on it.  The horror stories told on
> CompuServe were enough to convince me to stop using my Adaptec
> controller with an ST-225.  People have reported that they were not able
> to reformat their disks with their MFM controllers after abandoning
> RLL!! . . .

The real problem is the first one mentioned here -- if the media and electronics
of the drive are not certified for RLL they might work (I have a drive that I
used as an RLL drive for over a year with no problems and it will probably work
fine for as long as my RLL certified ST-238 (several diagnostics report no defects
and the MFM defect list was empty so I think the ST-225 is a bit better
surfaced than most, though).  On the other hand, the drive may work for a week
or two then start showing up soft errors (that just slow you down) or an
occasional hard error -- that goes away when you rewrite the data.  Both of
these conditions can lead you to think that it's working when it's not!  And
one day you discover that you can't boot, can't read any of your data files,
AND 2 MBYTES OF STUFF YOU PUT TOGATHER LAST MONTH ISN'T BACKED UP!!??!!  Not
worth the risk.

As far as damaging the drive, so far as I know the only way a controller can
damage a disk drive is by driving the stepper too hard, and a new MFM card
has all the same options to step at all those funny rates as the new RLL cards
-- that is to say, had the guy who couldn't format his drive after using an
RLL card been using a new WD controller with that same drive (and run a similar
"fast" interleave and step rate) he would have found his drive died running
the MFM controller.  Sigh, you have to be careful of overrunning ALL the
specs of old hardware and that's why you ought to put some weight to even
silly certifications if the data is important.  Talk to me about getting
software upgrades from Microsoft that aren't readable on 4 out of 5 machines!
Their duplicators or diskettes are substandard, I think.

[All to reiterate my subject line -- just losing data is bad enough!]

Charles Marslett
chasm@killer.UUCP