Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!aplcen!uakari.primate.wisc.edu!ames!purdue!bu-cs!ngeow
From: ngeow@bu-cs.BU.EDU (Yee Ngeow)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MFM as an RLL drive?
Message-ID: <44809@bu-cs.BU.EDU>
Date: 17 Dec 89 01:28:52 GMT
References: <887@crash.cts.com> <28373@amdcad.AMD.COM>
Reply-To: ngeow@cs.bu.edu (Yee Ngeow)
Followup-To: comp.sys.ibm.pc
Organization: Boston University
Lines: 39

In article <28373@amdcad.AMD.COM> phil@diablo.AMD.COM (Phil Ngai) writes:
>In article <887@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:
>|Possible, but not a good idea, especially with Seagate hard drives.  If you do
>|not format an ST412/506 drive as it is specified then the warranty is
>|invalidated.  I personally wouldn't risk it.  The moment of truth is right
>|after you format the drive RLL.  If you come up with a significant number of
>|bad tracks then it probably is a good idea to reformat it MFM, but again,
>|please don't do this to a Seagate drive, you will void the warranty.  If it's
>|out of warranty and you don't care if the drive might up and die, go ahead and
>|do it.
>
>Please stop repeating these untruths. Formatting an MFM drive as RLL
>will not physically hurt it. 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
  Please note that running an MFM drive as RLL DEFINITELY CAN HURT
it physically. Running an MFM at RLL push the drive electronics at
50% higher clock rate then an MFM. As with any electronic components, this
generates more heat, and if not dissipated qucikly enough, will cause
damage to the drive.

  Personal horror story:

  I formatted a Seagate ST-412 10Meg MFM drive (Yes, straight out of an
IBM PC/XT) using a WD 1002-27X RLL controller. It formats, yes, no problem. 
Did not give me one single bad sector. I was pretty happy, since now I get
15+ Megs out of the drive. After running it for 10 minutes, suddently it
went nuts, making really loud noise, and smell of burned plastic and soder
hit me. I turned it off immediately, and the logic board is totally fried.
I changed the logic board and it worked again. 

  Moral of story:   

  If you have a really old, pre-1984 drive, it is not wise to format it RLL.
It can certainly damage your drive electronics, but not the actual platter
mechanics. 


Kwong