RLL controllers with MFM drives
Ken Hoover
I have a Seagate ST225 in my XT (no flames on my obsolete machine); and
was wondering if getting an RLL controller for it would allow me to format
it out to 32 megs instead of the 20 I get now. My roommate and I were
puzzling over this one (he has an ST238, and we couldn't find any physical
differences), so I thought I'd submit it to the net.
- Ken
------------------------------------------------------------------------------
Ken Hoover [ con...@bingsuns.pod.binghamton.edu | con...@bingvaxa.BITNET ]
Resident computer jock and Mac hacker, SUNY-Binghamton Bio dept.
Senior undergraduate consultant, SUNY-Binghamton Computer Center
------------------------------------------------------------------------------
David Bank
DISCLAIMER: This is ** NOT ** a flame!
Sure, Ken. Go for it. Hook that MFM (i.e. NOT RLL-Rated) drive up to
that RLL controller, format it, and instant 50% more drive room. You
CAN do it. It'll even format.
If you're lucky, it might even hold data for a month before it starts
developing amnesia.
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.
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.
KIDDIES! Do NOT TRY THIS AT HOME!!!
If a drive is not SPECIFICALLY RLL-Rated by its manufacturer,
do NOT try hooking it to an RLL controller to boost storage. You
are playing Russian Roulette with your data and there is a VERY high
probability that you will lose everything.
If you want the space THAT badly, go out and buy yourself an
RLL-rated drive!
Unky Dave
unky...@shumv1.ncsu.edu
Brynn Rogers
> DISCLAIMER: This is ** NOT ** a flame!
> Sure, Ken. Go for it. Hook that MFM (i.e. NOT RLL-Rated) drive up to
>that RLL controller, format it, and instant 50% more drive room. You
>CAN do it. It'll even format.
> If you're lucky, it might even hold data for a month before it starts
>developing amnesia.
> 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.
> 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.
> KIDDIES! Do NOT TRY THIS AT HOME!!!
> If a drive is not SPECIFICALLY RLL-Rated by its manufacturer,
>do NOT try hooking it to an RLL controller to boost storage. You
>are playing Russian Roulette with your data and there is a VERY high
>probability that you will lose everything.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Dave's blanket statement
> If you want the space THAT badly, go out and buy yourself an
>RLL-rated drive!
>Unky Dave
>unky...@shumv1.ncsu.edu
I think that this is a little overboard. (or Dave sells drives)
One Manufacturer in particular (Maxtor) does not rate many of it's drives
RLL and yet I have had one running for over a month at almost double its
rated capacity. (A XT-1140 formats to 120 Meg MFM, I formatted it as a
XT-1240 RLL drive and got 204 Meg)
I talked to no less than six people who have been running MFM-rated
Maxtors as RLL drives and not one of them had a single complaint (and they
had a aggregate total time of more than ten years)
As I understand it, Maxtor uses plated media, and I have heard that the
main requirement for RLL is plated media. I talked with the tech support
people at maxtor and they said 'the XT-1140 is not RLL rated', but in
another sentence said 'Many of our customers run our drives RLL with no
problem' (But I had to drag it out of them.)
I don't doubt that taking a low end MFM drive and running it RLL can
give problems, But I strongly object to the blanket statement that you
CANNOT use a MFM drive with a RLL controller.
Some MFM drives will work RLL, some won't. About the only way to be sure
is to try it (But keep everthing backed up, and keep your MFM controller)
After getting an informal poll of people that use your drive RLL.
Brynn
Brynn Rogers Honeywell S&RC rog...@src.honeywell.com
home 612 874-7737
Galen Hekhuis
}>
}> I have a Seagate ST225 in my XT (no flames on my obsolete machine); and
}>was wondering if getting an RLL controller for it would allow me to format
A fairly common question, followed by
} DISCLAIMER: This is ** NOT ** a flame!
} KIDDIES! Do NOT TRY THIS AT HOME!!!
Including advice like sacrificing virgins, etc.
Oh poo. While I agree with the advice that it is a bit risky, and one
is better off getting an RLL certified drive for the extra bytes, it works
a fair percentage of the time, in my (humble) experience. As a matter of
fact, I currently have more (not by many) difficulties with genuine 238R
drives on RLL controllers than the 225s that I have stuck on them. It
isn't like you are going to blow up if you try this, just be aware that
it isn't the most reliable setup.
--
Galen Hekhuis UVa Health Sciences Center Box 449, Jordan Hall
Charlottesville, VA 22908 (804)982-1646 g...@virginia.edu
...there I was, standing in front of the fan...
David Bank
,. In response to Brynn Roger (rog...@src.honeywell.com):
Nope. I don't sell hard drives. I merely install and maintain
them and diagnose them when they go bad.
Contrary to your assertion, plated media is NOT the sole
basic difference in RLL-rated drives. The biggest single difference
is in the use of VOICE COIL technology in the armature control
mechanism. This is what allows the mush more closely controlled
head movement demanded by RLL. The plated media simply makes
for a more reliable rusty pie plate.
Sure, I know people running MFM drives on RLL too. Its
like the car you drive off the lot and it never needs to see a
mechanic. Some RLL drives are just able to do it. You may be running
them at the edge of tolerance, but you are just on this side of
their operational capacity. I never meant to say it was IMPOSSIBLE
to run an MFM drive on RLL. Merely dangerous with your data.
No, not a blanket statement at all. As I recall, I
qualified it with "probably".
Oops. Two paragraphs back, 3rd line, "RLL" should be "MFM"
These remote connections are hell on editing.
Unky Dave
unky...@shumv1.ncsu.edu
Keith Ericson
<In article <con...@bingsuns.cc.binghamton.edu (Ken Hoover) writes:
<>
<> I have a Seagate ST225 in my XT (no flames on my obsolete machine); and
<>was wondering if getting an RLL controller for it would allow me to format
<>
<
< If you're lucky, it might even hold data for a month before it starts
<developing amnesia.
<
< 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.
Well, it all depends on the quality of the drive (manufacturer?). I have
had absolutely no problems (zero, zip, nada) connecting an Adaptec 2372B RLL
controller to either Micropolis or Maxtor drives. Miniscribe: yes, problems
galore. Seagate: I wouldn't even _think_ of trying it...
kEITHe
David Bank
"Oh, poo" indeed!
As a professional, I would much rather overexaggerate the danger to
a slight degree than to underrate it.
There is a reason MFM drives are not RLL-rated: they were not
designed to meet RLL standards or performance. Period.
Yes, you CAN get away with it. But your hard drive is living on
borrowed time. Some drives can hack it, most can't.
I think I'd rather see 20 people go short drive room than I would
see 1 person lose his papers/research project/thesis/whatever to a
hard drive pushed beyond its limits.
(Yes, I realize I do not control other people or their computers.
The previous paragraph is merely my rationale for action.)
Unky Dave
unky...@shumv1.ncsu.edu
Paul Derks
> Contrary to your assertion, plated media is NOT the sole
>basic difference in RLL-rated drives. The biggest single difference
>is in the use of VOICE COIL technology in the armature control
>mechanism. This is what allows the mush more closely controlled
>head movement demanded by RLL. The plated media simply makes
>for a more reliable rusty pie plate.
Voice Coil technology has NOTHING to do whether a drive can do RLL or
only MFM. Most Seagate RLL drives use stepper motors and these drives
are fully RLL certified. Mechanically there is no difference between an
RLL or MFM drive. The main difference is that RLL uses a 7.5 Mbit/s
datastream and MFM 5 Mbit/s. This means that the electronics, the heads
and (maybe) the magnetic surface should be different (better). The reason
why better drives (Maxtor, Priam, Rodime) do RLL without problem is
because they have better specs.
However, I do agree that it is dangerous to use an MFM drive with an RLL
controller. In my experience ST 225's with RLL go bad after some time.
Even ST 238's go bad after some time. (I had one)
I have friends who use PRIAM V185 drives at RLL and this works perfectly.
(But they are RLL certified, I think). The drive I use is a Rodime 203E
and I have heard that it is RLL capable but not from a reliable source.
(i.e. the manufacturer self). Fact is that the drive works perfectly
with a WD 1003 RLL controller.
Paul Derks
CHRISTER OLSSON
> KIDDIES! Do NOT TRY THIS AT HOME!!!
>
> If a drive is not SPECIFICALLY RLL-Rated by its manufacturer,
> do NOT try hooking it to an RLL controller to boost storage. You
> are playing Russian Roulette with your data and there is a VERY high
> probability that you will lose everything.
>
> If you want the space THAT badly, go out and buy yourself an
> RLL-rated drive!
>
than 1%, you can use the drive with RLL. If the tolerance is near
1% or over, you shouldn't use drive with RLL.
Most drives is between 0.1 and 0.5% and can use RLL. For example,
the seagates typically has lower than 0.5% even if they are only
MFM-rated. (ST225, ST251 ..)
Ralf....@b.gp.cs.cmu.edu
> Contrary to your assertion, plated media is NOT the sole
>basic difference in RLL-rated drives. The biggest single difference
>is in the use of VOICE COIL technology in the armature control
>mechanism. This is what allows the mush more closely controlled
>head movement demanded by RLL. The plated media simply makes
>for a more reliable rusty pie plate.
RLL *does*not* need more closely controlled head movement, since it does
not change the number of cylinders on the drive. What RLL *does* need
is more accurate and cleaner amplification/processing of the data stream
coming off the drive. RLL and MFM both use the same number of flux
changes per second, but RLL requires more accurate timing on the flux
changes, since the timing carries information. This is analogous to
1200 and 2400 bps modems. 1200 bps modems are actually 600 baud, since
each change in the carrier transmits two bits of information, not just
one. 2400 bps are also 600 baud, but transfer four bits of information
per signal change, and thus require more accurate signal processing to
recover the information from the signal changes.
Unless your RLL controller magically increases the number of cylinders
on the drive, it will not demand any more accurate head movement than an
MFM controller for the same drive.
--
UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=-=- Voice: (412) 268-3053 (school)
ARPA: ra...@cs.cmu.edu BIT: ralf%cs.cmu.edu@CMUCCVMA FIDO: Ralf Brown 1:129/46
FAX: available on request Disclaimer? I claimed something?
"How to Prove It" by Dana Angluin
6. proof by omission:
"The reader may easily supply the details."
"The other 253 cases are analogous."
Wm E Davidsen Jr
If your 225 is the late model version it will probably work with the
RLL controller. See if the LED is the same color as your friend's 238. I
suggest the WD1006VSR2 controller if you have an AT bus.
--
bill davidsen (davi...@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
Steve Weinrich
> I have a Seagate ST225 in my XT (no flames on my obsolete machine); and
>was wondering if getting an RLL controller for it would allow me to format
>it out to 32 megs instead of the 20 I get now. My roommate and I were
>puzzling over this one (he has an ST238, and we couldn't find any physical
>differences), so I thought I'd submit it to the net.
I have read most of the replys to this poor man's question, and I
think that you have missed a point that I believe he was asking...
Is there a physical differnce? NO. The ST225 physical makeup
is the same as the ST238, the only difference is the quality (haha)
of it's plates. The only reason I know this is that when I sent in
a ST225 for repair, the person I spoke with on the phone said that
they (the re-work shop) could simply put in RLL rated plates and it
would be fine. [This is when I was working for a computer firm as
thier repair engineer] It would only increase the cost by a little
bit, so I said.. fine, do it. Sure enough, we hooked that puppy
up to an RLL and it worked just fine. Of course it did!
A perfect analogy for this whole situation is that of the difference
between a 360K disk and a 1.2 Meg disk. Sure, you can throw a 360K
rated disk (Double density) into a 1.2Meg and make it work, but you are
simply playing with fire... think about it, it's like recording your
favorite albums on the cheapest cassette that you could find. It *WILL*
store it, but then again, how good of a recording were you looking for?
Ah well, so much for replys... I think I will go back to bed...
-Steve
Lawrence F. Strickland
> In article <42...@ncsuvx.ncsu.edu> unky...@shumv1.ncsu.edu (David Bank) writes:
>> Sure, Ken. Go for it. Hook that MFM (i.e. NOT RLL-Rated) drive up to
>>that RLL controller, format it, and instant 50% more drive room. You
>>CAN do it. It'll even format.
>
>> If you're lucky, it might even hold data for a month before it starts
>>developing amnesia.
>
>
> One Manufacturer in particular (Maxtor) does not rate many of it's drives
> RLL and yet I have had one running for over a month at almost double its
> Some MFM drives will work RLL, some won't. About the only way to be sure
> is to try it (But keep everthing backed up, and keep your MFM controller)
This particular question seems to pop up over and over again, but there are
rarely any real solutions to it. Much of the problem seems to be related to
the drives used, not whether MFM drives will work as RLL in general.
Yes, the RLL encoding scheme is more intensive on the disk. Yes, formatting
an MFM drive as RLL may or may not work. About that question of it working
for a month or so and forgetting, well...
I thought for a considerable period of time before attempting to reformat
my 72 Meg Miniscribe drive as RLL. However, the 70 Megs was too small for my
application and I really didn't have the money to upgrade to a bigger drive and
several people said they didn't _think_ there would be any problem, so I went
ahead and reformatted.
It has been running for most of a year now with no data loss. The controller
card I used was the Adaptec which has been beaten up on the net but which has
worked well and, because of its on-board ROM, has allowed me to use both XENIX
and DOS together on the same drive.
My experience has been very positive and I recommend the Miniscribe line for
other reasons as well. So, if you have a Miniscribe, it seems likely that it
will work (at least the full-height 72 Meg drive :-)
-l
--
+--------------------------------------+-- St. Petersburg Junior College --+
| Lawrence F. Strickland | P.O. Box 13489 |
| ...!uunet.uu.net!pdn!jc3b21!larry | St. Petersburg, FL 33733 |
+--------------------------------------+-- Phone: +1 813 341 3321 ---------+
Terry Hull
I have been running a Priam ID-130 (MFM) drive formatted RLL for over
2 years under Novel with NO PROBLEMS. I have a 71 MB full height
Miniscribe that I used for 1 year MFM before I changed it to RLL, and
it has been running happily for 1.5 years now as a /usr/spool
filesystem on a computer that runs news. I also have a Maxtor 2190
formatted to 244 MB that has been running for 6 months with no
problems. Yes, there are problems with some drives, but just because
the drive is not rated RLL, does not mean that it will loose data
after a month or so. The bottom line is try it. It may work it may
not. BTW: I did have a Maxtor 2190 go flakey after 3 weeks when
formatted RLL, but I discovered it was flakey when formatted MFM also.
The only thing I do differently when using a MFM drive RLL, is I
tend to run extra passes through the diagnostic software to make sure
I get all the bad blocks before I put data on the drive.
--
Terry Hull
Department of Electrical and Computer Engineering, Kansas State University
Work: te...@eecea.eece.ksu.edu, rutgers!ksuvax1!eecea!terry
Play: te...@tah386.manhattan.ks.us, rutgers!ksuvax1!eecea!tah386!terry
Pete Holzmann
>a slight degree than to underrate it.
This I can agree with. But how much should we 'professionals' exaggerate the
danger? In my rather extensive experience with using MFM "rated" drives under
RLL, I can give you the following facts:
(1) Old Seagate ST-225's (and the identical ST-238's) are not good
under RLL. Don't try it! Supposedly, Rev 3 and up are better.
I'm still not ready to waste my time on one.
(2) Most, if not all (I've yet to see any hard facts that contradict
my 'all' here...) MFM/RLL pairs are absolutely identical hardware.
The only difference is that the ones sold with an RLL part number
have been specifically tested for RLL and are guaranteed to work
with an RLL format. ***What you get when you pay the extra bucks is
a guarantee that RLL will work. You do not get different hardware!***
(3) The **only** drive that I have ever personally seen fail to work
reliably with an RLL format is a Toshiba 56MB drive. And it *was*
rated for RLL!!! (Note that I avoid ST-225 upgrades...) I've done
a zillion Maxtors, ST-251's, and Micropolises. A few Miniscribes,
a few Priams.
Maxtor 1140's are especially nice, because a person can usually get
a full 1224 cylinders out of them (i.e. treat it as a 2190) instead
of the 'rated' 918. Yes, the extra cylinders are not under warranty,
so you need to do a good job of pre-testing before using them; most
customers are willing to take the time, in order to turn what is
guaranteed as a 120MB drive, into a very nice 230MB drive!
(4) The only drives I've heard of having any significant trouble are
Seagate and Miniscribe. Does this mean they are lower quality? You
judge for yourself!
(5) This is not a 'short term' problem or solution. I've been doing this
for a few years now, ever since RLL controllers became available. The
format does not deteriorate any more than MFM formatting does.
(6) Those who tell you that RLL requires more careful head positioning
or media capable of higher storage densities are blowing smoke. They
do not know what they are talking about. I don't have a copy any more,
but I wrote a few extensive articles a year ago explaining how RLL
works. Maybe somebody can send me a copy; I'll edit a few of the typos
and repost.
> There is a reason MFM drives are not RLL-rated: they were not
>designed to meet RLL standards or performance. Period.
Not true, except for earlier ST-225 drives. And the ST-238 labeled versions
of those drives, even though 'rated' for RLL, were very unreliable in an
RLL format. Those drives are what gave RLL a bad name.
> Yes, you CAN get away with it. But your hard drive is living on
>borrowed time. Some drives can hack it, most can't.
Unky Dave, you've got to be careful with your wording. The *worst* that
can happen is that your 'format is living on borrowed time'. RLL formatting
*never* will do physical damage to a drive!
> I think I'd rather see 20 people go short drive room than I would
>see 1 person lose his papers/research project/thesis/whatever to a
>hard drive pushed beyond its limits.
I'd rather let all 20 decide for themselves, with full knowledge of the
minimal risk involved.
Pete
--
Peter Holzmann, Octopus Enterprises |(if you're a techie Christian & are
19611 La Mar Ct., Cupertino, CA 95014 |interested in helping w/ the Great
UUCP: {hpda,pyramid}!octopus!pete |Commission, email dsa-contact@octopus)
DSA office ans mach=408/996-7746;Work (SLP) voice=408/985-7400,FAX=408/985-0859
Dwight Gordon
>In article <25...@bingvaxu.cc.binghamton.edu> con...@bingsuns.cc.binghamton.edu (Ken Hoover) writes:
>
>
>> I have a Seagate ST225 in my XT (no flames on my obsolete machine); and
>>was wondering if getting an RLL controller for it would allow me to format
>
> I have read most of the replys to this poor man's question, and I
>think that you have missed a point that I believe he was asking...
>
> Is there a physical differnce? NO. The ST225 physical makeup
>is the same as the ST238, the only difference is the quality (haha)
It didn't use to be so. Back when the ST238 was first introduced the
technicians (at the repair company for which I was consulting at that
time) did a comparison between the ST225 and the ST238. (Remember, the
RLL coding scheme originally was supposed to yield a 50% improvement
on _existing_ MFM drives.) The ST238's data circuit board was different than
the ST225s. (We did not have the equipment to check the media at
that time.) This may only have been a "standard" upgrade. But, depending
on the age of the ST225, it may have that "other" board. Seagate
advised us not to use the ST225 with a RLL controller, as they had
had some problems with some of them on the RLL controllers. (Note:
this whole experience was about 4 years ago. Things may have changed
since then.)
- Dwight -
--
Dwight W. Gordon, Ph.D. | 913-532-5600 | gor...@eecea.eece.ksu.edu
Electrical & Computer Engineering Department | dwgo...@ksuvm.bitnet
Kansas State University - Durland Hall | rutgers!ksuvax1!eecea!gordon
Manhattan, KS 66506 | {pyramid,ucsd}!ncr-sd!ncrwic!ksuvax1!eecea!gordon
Mike Richey
>
> Nope. I don't sell hard drives. I merely install and maintain
>them and diagnose them when they go bad.
> Contrary to your assertion, plated media is NOT the sole
>basic difference in RLL-rated drives. The biggest single difference
>is in the use of VOICE COIL technology in the armature control
>mechanism. This is what allows the mush more closely controlled
>head movement demanded by RLL. The plated media simply makes
>for a more reliable rusty pie plate.
This is not true. The difference between the ST225 and the ST238,
the miniscribe 8425 and 8438 is certainly not plated media any more, but
whether or not in the factory it passed the RLL tests. Neither of these drives
has a voice coil.
RLL PUTS NO MORE BITS ON A SURFACE than MFM. the DIFFERENCE is the
2,7 ENCODING -period-.
> Sure, I know people running MFM drives on RLL too. Its
>like the car you drive off the lot and it never needs to see a
>mechanic. Some RLL drives are just able to do it. You may be running
>them at the edge of tolerance, but you are just on this side of
>their operational capacity. I never meant to say it was IMPOSSIBLE
>to run an MFM drive on RLL. Merely dangerous with your data.
>
RLL has been aound for a very long time. It has been used with mainframe
drive systems since the early seventies. It's only recently that RLL
came to the PC market (like 1984).
Rodime made a number of drives (some that had plated media, some that didn't)
that were NOT rated for RLL, that simply worked with RLL. Novell used to sell
the Maxtor XT1140 hard disk drive in their NDS-2 and NDS-4 hard disk subsystem.
This drive enclosure included a SCSI (Adaptec 4070a) that had an ST412
interface that used RLL encoding. The Maxtor XT1140 is not or ever has been
RLL spec'd. There were a series of tests that Novell would run and these tests
were distributed with Netware to make sure the drive that was installed was
capable of handling RLL encoding. The installer was encouraged to run these
legthly tests on a drive that was to be installed. Know what, I've got dozens
of these drives on sites that have been going for >3 years, without a bit of
trouble. In fact, Maxtor began marketing a drive called the XT1240, that was an
RLL certified XT1140. Same drive, Same logic, same everything. Well different
serial number.
One of the differences from drive to drive is a device known as the pulse
detector. This device sits on the read/write head. It detects
the flux pulses that pass under it from the surface of the disk. This device
is a very important one. Silicon Systems is the company that supplies them
to Seagate and Miniscribe. The one that's used in the ST225 and the ST238
is not a current design. Silicon Systems still manufactures it specifically
for Seagate. Silicon Systems doesn't support the part anymore and has advised
Seagate to change the design because of faults that S.S. has fixed in
newer designs. But, Seagate uses the old one. Why? because the newer
one probably costs .12 more (my opinion). This little device is suspect
of causing intermittant problems with the ST225s and ST238s that drives
sometimes experience. I've had problems with ST2XX series where low level
formatting fixes the intermittant problems (or spinrite).
Well, without rambling on anymore......
Seagate tests all of their ST225 and ST238 drives at RLL first. If they
pass RLL, they're ST238s, if they fail, they test tham at MFM and ship
them as ST225s if they pass. This information I was told by seagate. This
only make economic sense if not logical.
Hey, you have a lot to offer, but no one is an expert on anything. No matter
how much you know, there's always some smart@ss out there that thinks they
know more 8-). So lighten up. And have a good today.
Michael S. Richey Internet: mri...@orion.oac.uci.edu
Bitnet: MRichey@UCI CompuServe: 71650,3132 Voice: (714) 856-8374
University of California, Irvine Network and Telecommunications Services
342 Computer Science Irvine, CA 92717
Wm E Davidsen Jr
| Seagate tests all of their ST225 and ST238 drives at RLL first. If they
| pass RLL, they're ST238s, if they fail, they test tham at MFM and ship
| them as ST225s if they pass. This information I was told by seagate. This
| only make economic sense if not logical.
Are you *very* sure about that? What I thought they told me was that
they tested drives until they had enough 238's. If a drive failed as a
238 it was retested as a 225. Therefore a 225 which you buy might be
either a drive which failed as RLL or one which was never tested. This
would explain why so many pass as RLL in actual service.
Mike Richey
We're saying the same thing here, except, I'm saying they do all of them
right away. To save money, test them all at RLL. If they need 225s they
label them as such. Another thing is that the controllers that go into PCs
are not so quite as tight on the specs as the devices that are used to
test the drives in the final test. The winchester testing units I'm
speaking of.
Regardless, the point was that there isn't any mechanical difference between
RLL and MFM drives. IMHO, i wouldn't buy a seagate of any king.
Drat CDC-Imprimis was just bought out by who??? yes, Seagate....
Well I'll take a positive outlook. The seagate product line
will improve drastically, rather than the CDC quality falling!!
Michael Richey
mri...@orion.oac.uci.edu
Phil Ngai
|basic difference in RLL-rated drives. The biggest single difference
|is in the use of VOICE COIL technology in the armature control
|mechanism. This is what allows the mush more closely controlled
|head movement demanded by RLL. The plated media simply makes
Here we have a self-proclaimed professional who hasn't the faintest
idea what he's talking about. I think you're just a parts-swapper, at
best. Tell me, smart guy, what is RLL and how does it work? Then you
can tell me what voice coils have to do with it.
--
Phil Ngai, ph...@diablo.amd.com {uunet,decwrl,ucbvax}!amdcad!phil
Just say NO to the "War on Drugs".
David Bank
Reply to Pete Holzmann:
As I have said a number of times, you CAN get away with it and I
in fact know people who have done so. I also know people who have had
their drive disappear from the list of ones DOS recognizes.
When I said "your drive is living on borrowed time" I ** NEVER **
meant to intimate that RLL would do physical damage to an MFM drive.
That is a ridiculous notion. You may be right in that a better choice
of words would have been "format" instead of "drive".
Unky Dave
unky...@shumv1.ncsu.edu
David Bank
Well, Mr. Ngai, I could respond in the same immature vein you did
and say:
"I think you're just a <INSERT RACIAL\ETHNIC\WHATEVER SLUR>"
but I think I'll exercise more self-control and intelligence than
you did. No point in sinking down to your level.
I generally have the respect for the net to keep flames in E-Mail,
but hey, if you want to start something, I'll happily finish it.
I feel absolutely no need to explain one damn thing to such a
rude and boorish person such as yourself. Next time try engaging
a CPU before your I/O.
Unky Dave
unky...@shumv1.ncsu.edu
Wm E Davidsen Jr
|
| 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.
Phil Ngai
| Well, Mr. Ngai, I could respond in the same immature vein you did
|and say:
|
| "I think you're just a <INSERT RACIAL\ETHNIC\WHATEVER SLUR>"
This is yet another lie. I used no racial\ethnic\whatever slurs.
Although I can believe that you often do.
| but I think I'll exercise more self-control and intelligence than
|you did. No point in sinking down to your level.
|
| I feel absolutely no need to explain one damn thing to such a
|rude and boorish person such as yourself. Next time try engaging
|a CPU before your I/O.
This is the kind of response you would expect from someone with little
knowledge and a big ego. I know your type. You're in a low-paying,
demeaning job swapping black boxes that you know nothing about. Maybe
you even graduated from high school. You're the lowest Indian on the
totem pole and your only sense of self-importance comes from snowing
any customers unlucky enough to talk to you. Unfortunately, Mr. Bank,
there are too many people on this net who do know what they're talking
about for you to get away with the kind of stuff you probably pull on
your customers.
Eric James Bales
All of this talk about the ST225's and 238's not being very
good at RLL format has made me wonder about my drive. I
swapped the 20 Meg in my PS/2 Model 30 for a ST138R when I
bought the computer used about eight months ago. Does the
ST138 (3.5 inch model of 238) have as much trouble as the
ST238? I am formatting(sp?) the drive RLL.
-Eric Kirkbride-
Carnegie Mellon
Disclaimer: Who, in their right mind, would believe me?!?
"I have a firm belief that all computers are the children of
Satan...", Shannon Cline
Paul Derks
>| Well, Mr. Ngai, I could respond in the same immature vein you did
>|and say:
>|
>| "I think you're just a <INSERT RACIAL\ETHNIC\WHATEVER SLUR>"
>any customers unlucky enough to talk to you. Unfortunately, Mr. Bank,
>there are too many people on this net who do know what they're talking
>about for you to get away with the kind of stuff you probably pull on
>your customers.
It already has been pointed out by several people on the net that Mr.
Bank absolutely doesn't know what he is talking about. It would have been
wise of Mr. Bank to say nothing more about the subject. I sympathize
with Mr. Ngai but I do think his response should have been less rude.
Perhaps it would be best if both Mr. Bank and Mr. Ngai reread the rules
about flames on the net.
Paul Derks.
j...@simpact.com
1325 in "RLL mode"? (I called the manufacturer and got the same answer
that someone else reported from Maxtor: "We don't support it, but a
lot of people are doing it.")
--- Jamie Hanrahan, Simpact Associates, San Diego CA
Internet: j...@simpact.com, or if that fails, j...@crash.cts.com
Uucp: ...{crash,scubed,decwrl}!simpact!jeh
J...@kuhub.cc.ukans.edu
> basic difference in RLL-rated drives. The biggest single difference
> is in the use of VOICE COIL technology in the armature control
> mechanism. This is what allows the mush more closely controlled
> head movement demanded by RLL. The plated media simply makes
> for a more reliable rusty pie plate.
>
> Sure, I know people running MFM drives on RLL too. Its
> like the car you drive off the lot and it never needs to see a
> mechanic. Some RLL drives are just able to do it. You may be running
> them at the edge of tolerance, but you are just on this side of
> their operational capacity. I never meant to say it was IMPOSSIBLE
> to run an MFM drive on RLL. Merely dangerous with your data.
>
> No, not a blanket statement at all. As I recall, I
> qualified it with "probably".
>
> Oops. Two paragraphs back, 3rd line, "RLL" should be "MFM"
> These remote connections are hell on editing.
>
> Unky Dave
> unky...@shumv1.ncsu.edu
This is NOT a flame, but I don't think the RLL-rated drives differ
from the MFM-rated ones based on the use of voice coil technology.
I am not sure how they related, but as far as I know, there are many
RLL-rated drives still using stepper motor to move the heads (such
as Miniscribe 8225, 8450, 8438, etc.) and MFM-rated drives using the
voice coil (such as Seagate 251-1, 4096, etc.). I haven't done much
research (at least not enough) on hard drives and their specifications,
but I failed to see how one can differetiate RLL and MFM rated drives
based on the use of voice coil.
By the way, I only see one person mentioned the different encoding
schemes that RLL and MFM systems (the encoding is done on the controller,
I think.) using, which should be the main difference between these two
types of systems. In order to meet the RLL specification, a drive
has to have better physical characteristics and media quality.
M.C. Baldwin
Dr. Scump
|
| Nope. I don't sell hard drives. I merely install and maintain
|them and diagnose them when they go bad.
|
| Contrary to your assertion, plated media is NOT the sole
|basic difference in RLL-rated drives. The biggest single difference
|is in the use of VOICE COIL technology in the armature control
|mechanism. This is what allows the mush more closely controlled
|head movement demanded by RLL. The plated media simply makes
|for a more reliable rusty pie plate.
|Unky Dave
|unky...@shumv1.ncsu.edu
What does voice coil have to do with it?
There are MFM voice-coil drives (e.g. ST40XX) and RLL stepper-motor
drives (e.g. ST2XXR, I think). These are two separate issues.
--
Alan S. Denney @ Informix Software, Inc.
{pyramid|uunet}!infmx!aland
David Bank
Mr. Ngai:
Oh, I just LOVE this. You "know my type:
Pity you don't know yourself.
I'd've been more than happy to Post the information you said I
didn't have. All it would have taken from you was a response devoid of
name calling, hysterics, and pathetic attempts at insults.
Instead, you CHOSE to attack me personally on the net. And then
you seem not to understand why I shouldn't have a charitable response
back.
Let's go over some facts, shall we, Mr. Ngai???
1) You don't know a damn thing about me. A few hundred bytes of
text does not a face-to-face meeting make.
2) You instigated the present state of affairs, complete with
the bandwidth waste as you Post ever more inaccurate
summations
of what I do and don't do for a living and how well I am
employed. Do you really think anyone out there in netland
gives a damn??? You're a bigger fool than you have already
made of yourself if you do.
3) My response to you has been the same as for anyone else
who would attempt to use the net as their own personal
soapbox in childish attempts to denigrate others. The
subject matter at hand is irrlevant.
Perhaps one day you'll learn how to be a human being. Let us know
when that happens.
John Eaton
< RLL and MFM both use the same number of flux
< changes per second, but RLL requires more accurate timing on the flux
< changes, since the timing carries information.
This is analogous to what happened when the floppy world went from Single
density to Double density. With single density a controller would write
a 8 us pulse for a 0 and two 4 us pulses for a 1. Double density added a
6 us pulse and was able to fit one bit in every 4 us by suitable encoding.
Note that the high and lows were the same and that they simply added a
pulse in the middle. A drive could smear a pulse by 2 us and work with
single density but could only smear by 1 us if it had to work with Double
density.
John Eaton
!hpvcfs1!johne
Peter Lim
From what I read from a book titled "????'s IBM-PC Hardware Bible",
can't quite remember the author's name, RLL differs from MFM on two
counts:
[1] The encoding method. RLL re-arrange the data using the 2,7
encoding method so that you always get a certain number of
consecutive 1's (I think 5 ??) in a 16 bit word. This arrangement
does two things: increase the number of raw bits to be written on
disk for the same amount of data, and reduce the flux density
for the same amount of raw bits to be written on the disk.
[2] Increase the number of sectors per track from 17 (MFM) to 26;
which gives about 50% more capacity.
You increase the amount of data to be written to disk and put more
sectors on one track, but reduce the inter-bit flux density.
According to the author, it works out that for an increase of flux
stress of about 14%, you get 50% more capacity. Reasoning goes that
this 14% extra stress is well within the tolerance of most recent
MFM drives, so they can be used as RLL drives.
My brother has been using Seagate MFM drives for RLL for more than
a year and had no problem at all. I haven't got my own system yet,
but I think I will just go ESDI instead :-). I hope the above explains
something. Sorry I didn't memorize the numbers and probably phrase my
sentenses badly........ but that's what you get of two-cent's worth
:-).........
Regards,
Peter Lim.
HP Singapore IC Design Center.
E-mail address: plim@hpsgwg
Snail Mail address: Peter Lim
Hewlett Packard Singapore,
(ICDS, ICS)
1150, Depot Road,
Singapore 0410.
Telephone: (065)-279-2289
wayne ho
> 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.
>
>
>
I do agree with you that putting RLL controllers on MFM drives
is quite a risk, but I must say, it isn't impossible. I have RLLed
an ST-225 and a Miniscribe 3650 (which is exactly the same drive as
the RLL rated 3650.. 'cept its not certified) for a year or so now
without a hitch.
Yes, I may be slightly crazy, but most of my data is not EXTREMELY
important. I have backups.. From what I know Seagate no longer allows
their non-RLL certified drives to use RLL. They have done something
with their drives to disallow this. In their older ST-225's RLLing
is possible, but it isn't very safe. I suppose I was lucky. From
what I know you need a ST-225 above revision 3. I'm not sure when
they started changing their drives to disallow RLLing.
Oh, BTW, I will tell you if my drives crash.. but by that time,
it may not be due to the RLL (these drives are pretty old).
Wayne
--- ConfMail V3.31
* Origin: MeTaStAsIo'S -`Not ready error reading drive A' (416)487-9093 (1:250/526)
Goran Larsson [Hacker of Hackefors]
>Has anyone had notable success or notable problems using a Micropolis
>1325 in "RLL mode"? (I called the manufacturer and got the same answer
>that someone else reported from Maxtor: "We don't support it, but a
>lot of people are doing it.")
One of the disks in my UNIX machine (not pc :-) is a 1325 and it has been
running continuosly with a RLL controller for the last 6 months without
any problem. The root filesystem is located on this disk so the disk is
used heavily. I'm using the Adaptec ACB4070 RLL controller.
I'm also using RLL on a Quantum 640 without problems.
! _
! ! Goran Larsson [The Hacker of Hackefors]
--+-! Hackefors, Linkoping, SWEDEN (See) +46 13-155535 (Hear)
!-+-- ...!uunet!sunic!liuida!prodix!isadora!hacker (UUCP)
! ! hac...@isadora.ikp.liu.se (Internet)
! Mmh, Yes
Wm E Davidsen Jr
| From what I know Seagate no longer allows
| their non-RLL certified drives to use RLL. They have done something
| with their drives to disallow this.
Where did you get this info? 225's up to date code May89 seem to work
okay. Seagate has *always* told you not to do it, but as far as I can
tell that's the only thing they've done.
Let's verify or squash this story.
John C. Archambeau
>Hello there,
> I do agree with you that putting RLL controllers on MFM drives
>
>is quite a risk, but I must say, it isn't impossible. I have RLLed
>an ST-225 and a Miniscribe 3650 (which is exactly the same drive as
>the RLL rated 3650.. 'cept its not certified) for a year or so now
>without a hitch.
> Yes, I may be slightly crazy, but most of my data is not EXTREMELY
>
>is possible, but it isn't very safe. I suppose I was lucky. From
>what I know you need a ST-225 above revision 3. I'm not sure when
>they started changing their drives to disallow RLLing.
an authorized Seagate dealer that Seagate NEVER condoned RLL formatting a
non-RLL certified drive. Same goes in reverse, if you MFM format an RLL
drive, the warranty is invalidated. But I do know one thing, Seagates if
formatted the way they're supposed to be never gave me any trouble. I have a
two year old ST225 to prove it. The only time it crashed was when *I* had the
pleasure of trashing the partition table myself. Of course, that ST225 is now
in the hands of a friend of mine whom I sold it to and replaced with an ST151.
Oh, by the way. Seagate is not going to develop anymore MFM or RLL drives.
The ST151 was Seagate's last MFM drive developed. Seagate is now focusing on
SCSI drives so now this problem of MFM and RLL will be done with as soon as
the older MFM and RLL drives die out from normal usage. Seagate will still do
servicing of these drives of course, but gradually, they will cease
manufacturing of MFM and RLL drives. There will be no 80 Mb 3.5" MFM or RLL
drive, only a SCSI drive. A shame since the newer 3.5" drives have an average
access time of 24ms (ST151, ST177N, and ST1096N). Guess I'd better buy my 2nd
ST151 while I can. Got another hard drive bay to fill up. :)
/*--------------------------------------------------------------------------*
* Flames: /dev/null (on my Minix partition)
*--------------------------------------------------------------------------*
* ARPA : crash!pnet01!j...@nosc.mil
* INET : j...@pnet01.cts.com
* UUCP : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca
*--------------------------------------------------------------------------*
* Note : My opinions are that...mine. My boss doesn't pay me enough to
* speak in the best interests of the company (yet).
*--------------------------------------------------------------------------*/
Ed Hall
>In article <8910291...@masnet.uucp>, wayn...@f526.n250.z1.fidonet.org (wayne ho) writes:
>| From what I know Seagate no longer allows
>| their non-RLL certified drives to use RLL. They have done something
>| with their drives to disallow this.
>
> Where did you get this info? 225's up to date code May89 seem to work
>okay. Seagate has *always* told you not to do it, but as far as I can
>tell that's the only thing they've done.
Well, when I tried to reformat my year-old ST-4096 with a WD-1006V-SR2
controller (a 1:1 RLL controller), just about *half* (50%) of the
tracks came up bad, according to WD's ROM-based formatter. Seagate
claims this is a plated-media, voice-coil-positioned drive--so by what
I've read (here and elsewhere) it *should* run RLL despite any lies
Seagate has been telling about MFM/RLL incompatability. But nothing I
did would make it take an RLL format.
So, I popped back in the old WD MFM controller and reformated. ZERO
bad tracks! (I had to mark the bad tracks listed on the drive manually.)
One more go with the RLL controller yielded the same sad results as the
first time. So the disk and MFM controller are now running happily in
my father's AT, and I'm running an old, noisy, slow (and too small!)
MiniScribe 3650 formatted RLL until I can replace it with an RLL-rated
(or at least RLL-quality) drive. (The 3650 RLL'd perfectly!)
Now, I understand the difference between 1,3 RLL (aka MFM) and 2,7
RLL, and can see no reason why the latter would perform so poorly on
the ST-4096 unless Seagate either used exceptionally poor head
electronics (much worse than a MiniScribe drive a year older and three
times cheaper), or they intentionally engineered that electronics to
prohibit 2,7 RLL.
Perhaps I should post to alt.conspiracy. I've certainly read of
ST-4096's running RLL. I might just be unlucky.
(The drive was manufactured in October of 1988, for those who care.)
-Ed Hall
edh...@rand.org
wayne ho
I have read information for a hard drive conference about this.
I should have said, I HEARD this, rather than said I KNOW this. I
can't say what they have or have not done, for sure. If I find anymore
information regarding this topic, I'll let you know.
Perry Hutchison
> I work for an authorized Seagate dealer ... Seagate NEVER condoned RLL
> formatting a non-RLL certified drive. Same goes in reverse, if you MFM
> format an RLL drive, the warranty is invalidated.
I asked this once before, but now that we have someone with direct Seagate
knowledge maybe we can get a semi-authoritative answer. It's pretty clear
from previous postings that using RLL on a drive not designed for it is
not always going to work, and one can therefore not expect a manufacturer
to warrant the results.
What I don't see is why Seagate objects to MFM formatting of an RLL-rated
drive. Obviously it reduces the capacity by 1/3, but if someone wanted to
do it, would it really impair the reliability so as to justify voiding the
warranty?
Pete Holzmann
>Well, when I tried to reformat my year-old ST-4096 with a WD-1006V-SR2
>controller (a 1:1 RLL controller), just about *half* (50%) of the
>So, I popped back in the old WD MFM controller and reformated. ZERO
>Perhaps I should post to alt.conspiracy. I've certainly read of
>ST-4096's running RLL. I might just be unlucky.
These symptoms are very similar to what I saw the one time I had a drive
that simply refused to 'take' RLL. In my case, it was certified for RLL,
so I just yelled until I got a replacement. (It was actually pretty tough-
the distributor had an MFM tester, not an RLL tester. The drive worked
perfectly under MFM; I had a time convincing them it was bad!)
I never got a truly satisfactory answer out of the manufacturer's field
engineer. Supposedly it had something to do with a portion of the mechanical
assembly not being tightened down quite enough; the drive would eventually
have failed under MFM also. By the way, it had a huge pile of defects listed
on its RLL defect map also. I suppose I should have been suspicious from the
start!
Wm E Davidsen Jr
|
| Now, I understand the difference between 1,3 RLL (aka MFM) and 2,7
| RLL, and can see no reason why the latter would perform so poorly on
| the ST-4096 unless Seagate either used exceptionally poor head
| electronics (much worse than a MiniScribe drive a year older and three
| times cheaper), or they intentionally engineered that electronics to
| prohibit 2,7 RLL.
I think the complete text of my posting included the word "most."
Since the drives sold for MFM are not tested for RLL timing accuracy,
you could get a unit which doesn't hack it. Remember that the TOTAL
timing jitter in drive, drive electronics, and controller is the
determining factor. You could have a controller which is in spec but not
better than spec.
|
| Perhaps I should post to alt.conspiracy. I've certainly read of
| ST-4096's running RLL. I might just be unlucky.
A lot of us have run 4096s and 251s RLL happily. I have done about six
of these installations, and I haven't had any trouble. The sixhub
archive server is running on one, and that has been very reliable.
wayne ho
> You mean the drive won't format RLL or what?
I may have been mistaken here. I heard read it somewhere in another
echomail conference and thought it came from a reliable source. I
have no proof with this, so until anyone else has information on SEAGATE
and RLL stuff, I won't worry about it.
> Oh, by the way. Seagate is not going to develop anymore
> MFM or RLL drives.
> The ST151 was Seagate's last MFM drive developed. Seagate
> is now focusing on
> SCSI drives so now this problem of MFM and RLL will be
> done with as soon as
> the older MFM and RLL drives die out from normal usage.
So SCSI is the way to go?? I was thinking about purchacing a SCSI
controller and drive for my 386sx, but I have been warned against purchacing
a 16-bit SCSI controller. Again, I don't know if this is true or not,
but someone told me that the 16-bit SCSI doesn't not work that well.
I was considering an 8-bit SCSI controller, what do you think? Also,
what types of SCSI drives does Seagate have out at the moment? If
you have any specs such as speed and size that would be nice to know.
Thanks in advance.
John C. Archambeau
>I asked this once before, but now that we have someone with direct Seagate
>knowledge maybe we can get a semi-authoritative answer. It's pretty clear
>from previous postings that using RLL on a drive not designed for it is
>not always going to work, and one can therefore not expect a manufacturer
>to warrant the results.
>
>What I don't see is why Seagate objects to MFM formatting of an RLL-rated
>drive. Obviously it reduces the capacity by 1/3, but if someone wanted to
>do it, would it really impair the reliability so as to justify voiding the
>warranty?
he formatted an RLL drive MFM and it didn't quite work the way it was supposed
to. I do know Seagate's warranty policy well and I follow it to the letter.
It might deal with the fact that an RLL drive is designed to do a 7.5 Mbit/sec
transfer and an MFM drive is only 5.0 Mbit/sec. But I do know that it is
documented on page 6 of the Seagate Universal Installation Guide. The
copyright date on it is '87, but we have been getting this installation
booklet with every drive we have ordered.
Keith Ericson
>Since the drives sold for MFM are not tested for RLL timing accuracy,
My _guess_ would be that "the drives sold for MFM" really _are_
tested for RLL and fail...
kEITHe
Keith Ericson
> > Oh, by the way. Seagate is not going to develop anymore
> > MFM or RLL drives.
> > Seagate is now focusing on
> > SCSI drives so now this problem of MFM and RLL will be
Seagate has purchased/absorbed/taken over Imprimis, formerly known
as CDC, one of the foremost manufacturers of SCSI drives. I only
hope the Seagate-ness doesn't rub off on Imprimis...
>So SCSI is the way to go?? I was thinking about purchacing a SCSI
>controller and drive for my 386sx, but I have been warned against purchacing
>a 16-bit SCSI controller. Again, I don't know if this is true or not,
>but someone told me that the 16-bit SCSI doesn't not work that well.
>I was considering an 8-bit SCSI controller, what do you think? Also,
>what types of SCSI drives does Seagate have out at the moment? If
>you have any specs such as speed and size that would be nice to know.
A 16-bit controller has a better chance of achieving maximum
transfer rate than does an 8-bit. I measure (using Core27) a
transfer rate of about 1.4Megabytes (yes, 1,400 kilobytes) per
second with an Adaptec 1542A/Imprimis94181-702 (617.4 Megabytes
formatted) in an Everex STEP/25. With the Seagate ST-)2 I got (as I
recall) certainly no better than 450 Kbytes/sec (if even that good;
as I recall it acted like a 2:1 MFM drive as far as transfer rate is
concerned).
My suggestion is to only purchase the ST-02 (or -01) if you simply
cannot afford one of the better (16 bit) controllers. It's like
hooking up a 50-amp power supply with a 1/4 amp fuse.
kEITHe
John C. Archambeau
>Hello,
> I may have been mistaken here. I heard read it somewhere in another
>echomail conference and thought it came from a reliable source. I
>have no proof with this, so until anyone else has information on SEAGATE
>and RLL stuff, I won't worry about it.
>
> > MFM or RLL drives.
> > is now focusing on
> > SCSI drives so now this problem of MFM and RLL will be
>
> > the older MFM and RLL drives die out from normal usage.
>
>controller and drive for my 386sx, but I have been warned against purchacing
>a 16-bit SCSI controller. Again, I don't know if this is true or not,
>but someone told me that the 16-bit SCSI doesn't not work that well.
>I was considering an 8-bit SCSI controller, what do you think? Also,
>what types of SCSI drives does Seagate have out at the moment? If
>you have any specs such as speed and size that would be nice to know.
Not quite yet. I wouldn't buy a SCSI hard drive unless your motherboard has
a built-in SCSI port (I have seen some) or until companies such as Western
Digital design a good 16-bit or 32-bit SCSI host adaptor. There might be such
a beast out now. I think I remember seeing an ad for a 32-bit SCSI host
adaptor in a magazine (MIPS?), but I can't for the life of me remember who
made it. As for which SCSI drives Seagate has out now, they have the
following:
5.25" (these are basically SCSI implementations of their MFM/RLL
counterparts):
ST225N (20 Mb), ST251N (40 Mb), ST277N (60 Mb), ST296N (80 Mb)
3.5" Drives:
ST125N (20 Mb), ST138N (30 Mb), ST157N (46 Mb), ST177N (60 Mb)
ST1096N (80 Mb)
These are the more common units out there that I can think of from the top of
my head. I had the latest data booklet from Seagate a week ago but I think my
one of our assinine sales reps ate it or gave it to a customer. The newer
3.5" drives by Seagate have an average seek of about 24ms which is better than
the old STblah-1 units with only 28ms. I do recall seeing some drives with a
20ms seek in that booklet, but that's just a vague memory since my primary
concern was with the newer 3.5" drives. I just bought an ST151 which is
basically a 3.5" version of the ST251-1 with a seek of about 24ms. I like it
and until the SCSI host adaptor card is resolved with the IBM compatables
entirely, I will stick with MFM and RLL drives for the time being. I'm not
convinced of the reliability of SCSI ports for the IBM compatable domain as of
yet. I do know that Seagate does make pretty sloppy drive controllers and
host adaptors. I base this on the fact that they recommend an interleave of
3:1 on an AT and 4:1 on an XT while I can easily get a 2:1 with my WA3-16 (a
WD1003-WA2 clone more or less) or a WD1006V-MM2 that I just put in an Arche
Rival 286-12 today. I do admit that Seagate makes good drives, but I don't
like their controller and host adaptor boards. In that department I'm partial
to Western Digital. When WD makes a 16-bit SCSI host adaptor that's been
around for awhile, then I might contemplate a SCSI hard drive, but not till
then.
When Seagate Dealers and Distributors can't order the MFM and RLL drives
anymore, then I would start to break my piggy bank for a SCSI host adaptor and
SCSI hard drive, but not until I see that bridge on the horizon which probably
won't be for a few years to maybe a decade depending on where the demand is.