From: ajb8886@ritvax.isc.rit.edu
Subject: Re: Use RLL drive w/ MFM Controller?
Reply-To: ajb8886@ritvax.isc.rit.edu
Organization: Rochester Institute of Technology
Date: Wed, 30 Sep 1992 22:30:12 GMT

In article <1662@frackit.UUCP>, dave@frackit.UUCP (Dave Ratcliffe) writes:
>In article <1992Sep24.202654.23574@csx.cciw.ca>, u009@csx.cciw.ca (G. Stewart Beal) writes:
>> In article <1992Sep24.123857.43306@kuhub.cc.ukans.edu> 2fubgarble@kuhub.cc.ukans.edu (Jason L. Wilson) writes:
>> >...
>> >support.  Is it posible to use the 30MB RLL drive as a 20MB MFM drive
>> >with the controller I have or will I have to purchase an RLL contoller?
>
>> Should work fine. Running a MFM drive on a RLL controller, though
>> is asking for problems.
>
>Sorry but I have to object to your generalization. In SOME cases it's a
>Bad Thing [tm] to run an MFM drive as an RLL but this is definately NOT
>generally the case. I administer 2 different Unix sites running MFM
>drives as RLL (all are Maxtor drives, 2 XT-1140's 1 XT-1085 and 1
>XT-2190). All run on DTC 7287 controllers. All are, and have been,
>running flawlessly. The XT-1140's for 4 1/2 years. Anyone who knows Unix
>knows it's NOT a drive friendly system since the drives are nearly
>always running for something. 
>
>My DOS machine is running a Priam V-185 and a Miniscribe 8425F.  Both
>are running flawlessly and the controller is also a DTC 7287. I have
>also run, in the past, an AT&T 6300+ under DOS with an Adaptec RLL
>controller and a Seagate ST-238 MFM drive. Ditto, no problems.
>
>Hell, I even used an antique IMI 10 meg drive under RLL for a short time
>and except for it being slower than molasses in January even IT ran
>flawlessly. 
>
>Of all the MFM drives I have fired up under RLL controllers only an
>ancient Seagate failed to funtion properly (lost data, excessive bad
>sectors after a few days, etc.). 
>
>This is not to say that ALL MFM drives can be safely used as RLL.  I
>just want those who are interested and new to playing with hardware to
>know that in many cases it CAN be done and fairly safely. 
>
>WARNING ----- If you DO try to run an MFM drive as RLL, MAKE SURE IT'S
>RELIABLE BEFORE TRUSTING YOUR IMPORTANT DATA TO IT. 
>
>Oh, and as for the original question, Yup, you CAN use an RLL drive with
>an MFM controller but its kinda like dropping a VW bug engine into a
>Formula IV racer :)
>
>
>
>
>
>-- 
> ...uunet!wa3wbu!frackit!dave -or-                       |  Dave Ratcliffe  |
> frackit!dave@uunet.UU.NET -or- dave@frackit.uucp -or-   |  Sys. <*> Admin. |
> vogon1!compnect!frackit!dave@psuvax1.psu.edu            | Harrisburg,  Pa. |

I'll second that.

I'm well aware that some MFM drives can be safely used with an RLL controller
(I do it myself with an Imprimis 72MB formatted to 110MB, it passes the deepest
testing Spinrite and DiskTechnician can put it through.)

On the other hand, I've tried this with many different drives; certain
brands/models do >not< work reliably this way.  The model most likely to
fail formatted RLL (ie. would develop "transient" bad sectors...sometimes
there, sometimes NOT) was the old Seagate 4096 (80MB MFM).  Then again, it
was likely to fail formatted MFM as well :).

Alex