Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!pyramid!prls!philabs!ttidca!quad1!avatar!kory
From: kory@avatar.UUCP (Kory Hamzeh)
Newsgroups: comp.unix.xenix
Subject: Re: Questions about RLL controllers
Summary: Do use MFM drives
Message-ID: <103@avatar.UUCP>
Date: 11 Feb 89 03:04:07 GMT
References: <3700022@eecs.nwu.edu>
Organization: Kory Hamzeh, Canoga Park, Ca, USA
Lines: 45

In article <3700022@eecs.nwu.edu>, skrenta@eecs.nwu.edu (Richard Skrenta) writes:
> Are there any dangers associated with using an RLL controller on drives
> only certified for MFM?  Could the controller damage the drive in any
> way, or is it just a matter of mapping a few more bad tracks during the
> format?  I noticed there are some nasty warnings in the Seagate manual
> about voiding your warranty if you use the wrong controller with a drive.

Do NOT use MFM drives with a RLL controller. I am speaking from very bad
experience. I bought 2 Rodime RO3055 drives and where told by the dealer
that these drives are RLL. Being the trusting kinda fella that I am, I didn't
bother to check with Rodime. Well, the drives worked flawlessly for the first
month or two. After that, I would start getting a new bad sector a day. It
got to the point that the drives were not usable. Reformatting helped a bit,
but the problems would re-appear in about a month later.

I assumed that just because the drives where plated, they were RLL 
compatible. Wrong assumption. The drives MUST be RLL certified by the
manufacturer.

> Also, where does the extra space come from?  Do RLL controllers increase
> the sectors per track or the number of tracks?  How would I get Xenix to
> recognize the new space?

The extra space come from the fact that RLL controllers use a different
encoding technique which allows them to basically compress more data on
each track. There are two different encoding methods. One methods increases
your capacity by 50% and the other by 100%.

When the controller is initialized, it over write the standard drive table
with its own. Xenix will read this table during installtion. I use the
Adaptec controller (ACB2732???) and have had absoulutely no problems
with Xenix or Mess-Dos.

I would like to hear from people that use the 100% increase controller.
Who's controller and drive are you guys using?


--kory



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