[comp.sys.att] 1024 CYL versus WD2010

jcm@mtunb.ATT.COM (was-John McMillan) (08/03/89)

If I recall correctly, two recent notes seemed to assert that
WD2010 chips were needed -- and I couldn't see why.

Eg:
In article <254@gnosys.UUCP> gst@gnosys.UUCP (Gary S. Trujillo) writes:
>I recently discovered a Boston-area source (which does mail-order) for
>the Micropolis model 1355, which has a formatted capacity of 159 Mbytes
>(it's 170 Mbytes unformatted).  The drive has eight heads with 1024
					       ^^^^^^^^^^^      ####
>cylinders, so I'm assuming it wouldn't require the P5.1 upgrade, though
						    ^^^^^^^^^^^^
>it would need the WD2010 chip (right?).
		   ######	====== -- No, I don't think so.
:
:
** LET'S AGREE THAT AN ESDI DISK IS IN-APPROPRIATE:  I READ THAT NOTE! **
				    --------------

_MY_ question is:
	WHY does anyone think the WD2010 is necessary for <= 1024 CYL?
							     ^^^^^^^^
So far as _I_ know, the WD1010 will suffice for
		any ST-506 disk <= 1024 CYL. (*)

I'd have skipped the whole matter, but I think someone else made the
same assertion in another note.  Perhaps I've missed some key feature
of this chip I should know about...

(*) -- OK, some ST-506 are better than others, as another note mentioned.
	And some disks require a kick-start, or table bang:  it's NOT
	the 3B1 here, fellahs.

john mcmillan	-- att!mtunb!jcm

jan@bagend.UUCP (Jan Isley) (08/04/89)

In article <1581@mtunb.ATT.COM> jcm@mtunb.UUCP (John McMillan) writes:
>If I recall correctly, two recent notes seemed to assert that
>WD2010 chips were needed -- and I couldn't see why.

Various very logical and correct points deleted.

>I'd have skipped the whole matter, but I think someone else made the
>same assertion in another note.  Perhaps I've missed some key feature
>of this chip I should know about...

Well, about a year ago I alluded that there was maybe something more to
say for a 2010 than the 1024 cylinder limit.

I had been running a Seagate 4096 for a few months with a "variety" of
intermittent read/write problems and a steadily growing bad block table.

I needed to test a Microscience 1090 so I put in a 2010 chip, ran the 
1090 for a few days, then put the 4096 back in.  Guess what?  No more
hard disk problems.  Hmmm....  I put the original 1010 back in ...
problems came back.  I put in a different 1010 ... still disk problems.
Reformat the drive ... still problems.  2010 back in, problems went away.
Reformat the 4096 ... bad blocks went away.  That was six months ago.
*NO* more problems on this disk.

Beats me.  You figure it out.

Jan
---
jan@bagend | gatech!bagend!jan | h (404)434-1335 | w (404)425-5700

	Humankind cannot bear very much reality.   T. S. Eliot

kevin@kosman.UUCP (Kevin O'Gorman) (08/04/89)

In article <820@bagend.UUCP> jan@bagend.UUCP (Jan Isley) writes:
> Prologue deleted
>
>Well, about a year ago I alluded that there was maybe something more to
>say for a 2010 than the 1024 cylinder limit.
>
>I had been running a Seagate 4096 for a few months with a "variety" of
>intermittent read/write problems and a steadily growing bad block table.
>
>I needed to test a Microscience 1090 so I put in a 2010 chip, ran the 
>1090 for a few days, then put the 4096 back in.  Guess what?  No more
>hard disk problems.  Hmmm....  I put the original 1010 back in ...
>problems came back.  I put in a different 1010 ... still disk problems.
>Reformat the drive ... still problems.  2010 back in, problems went away.
>Reformat the 4096 ... bad blocks went away.  That was six months ago.
>*NO* more problems on this disk.
>
>Beats me.  You figure it out.

Dunno.  I've got a 4096 that I've been running with my 7300 for about 3
years.  I ran it for a while in a stock configuration, and for about a
year now with the P5.1 upgrade.  I had the disk die on me once with a
growing bad block table, but that turned out to have been caused by
humidity damage (I used to live in New Jersey, where some summer days
are distinctly moist).  It has had the original 1010 the whole time.

The current replacement disk had been running fine for two years.  Nary
a glitch or a retry in the log.

You figure it.

thad@cup.portal.com (Thad P Floryan) (08/05/89)

Jan Isley comments:

"	I needed to test a Microscience 1090 so I put in a 2010 chip, ran the 
	1090 for a few days, then put the 4096 back in.  Guess what?  No more
	hard disk problems.  Hmmm....  I put the original 1010 back in ...
	problems came back.  I put in a different 1010 ... still disk problems.
	Reformat the drive ... still problems.  2010 back in, problems went away.
	Reformat the 4096 ... bad blocks went away.  That was six months ago.
	*NO* more problems on this disk.

	Beats me.  You figure it out.
"

This is my observation, too, using the WD2010 chip.  Been testing one of them
very heavily the past 7 days with 9 different disks (all <= 8 heads and <= 1024
cylinders); disks that were previously "bad" are now operating as if they all
had perfect media.

Though ALL of WD's literature states (paraphrased) the WD2010 is 100% software
compatible with the WD1010, it appears the onboard ECC (Error Correction and
Control) circuitry (which is NOT present on the WD1010) is doing a lot of good
voodoo and other "magic."  In other words, the WD2010 is a good replacement
for the WD1010 even if one doesn't wish to install a humongous HD possessing
more than 1024 cylinders.

Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]