Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!wuarchive!wugate!uunet!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.sys.ibm.pc
Subject: Re: RLL controllers with MFM drives
Summary: hogwash
Message-ID: <1413@crdos1.crd.ge.COM>
Date: 24 Oct 89 12:41:47 GMT
References: <none> <2546@bingvaxu.cc.binghamton.edu> <4265@ncsuvx.ncsu.edu>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: GE Corp R&D Center
Lines: 31

In article <4265@ncsuvx.ncsu.edu>, unkydave@shumv1.uucp (David Bank) writes:
|  
|     RLL is a MUCH more demanding format and less tolerant of errors. MFM
|  drives are not RLL rated for a very good reason -- they can't deliver
|  the performance RLL-controllers demand. They are very simply not
|  engineered for the rigors of RLL usage.

  Fact: RLL rated drives are made on the same lines as MFM. The RLL
drives are tested for rotational speed regularity and accuracy of the
PLL. An MFM drive may have failed those tests, or may not have been
tested. There are no engineering diferences.
|  
|     So...you CAN do what you want. But you had better hope and pray
|  and sacrafice virgins to Mammon or that drive WILL crash. Not might.
|  WILL. It is only a matter of time before you get "Disk Boot Error"
|  or "Invalid Drive Specification" or some similar, sinister, error
|  message.

  This is true, if misleading. Every drive will eventually fail. People
who tell you that RLL is "harder on the drive" are kidding themselves.
The only failure which hits RLL before MFM on any given drive would be
bearing drag. If you go MFM you might run another 100 hours or so before
they fail. I have never seen this happen, usually either the electronics
go or a head comes in for a landing.

  Backups are improtant with ANY disk.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon