Mylex SCSI Controller, 16550A U

neese at adaptex.UUCP neese at adaptex.UUCP
Wed Oct 11 07:07:00 AEST 1989

>The WD series also has better ECC capability demonstrated on the
>bench, it can recover data from marginal drives that the Adaptec will error
>out on.  As an example, we have one ST4144 right here in the shop that shows 
>~30 errors with our diagnostic software using the WD1006, and some 200 (!)
>errors on the >same< drive using a 2372.  This is a shop drive; I'd never
>put that thing in a box for a customer, but it does demonstrate the superior
>data recovery abilities of the WD card.  Adaptec claims to have the best
>data separation capability; they're full of hot air.  Our actual field tests 
>don't bear out their claims.
>You know which board I'm going to trust my data to given a choice, don't you?

Well, I don't want to start a flame war here, but here are some facts about
both controllers.  

1) By default, the 2372 does zero retries to get data from a
device.  The WD controller does 8 retries no matter what.  The 2372 does
not do retries unless the system it is running in requests them.  This alone
will account for the difference in errors.
2) The data separator has nothing to do with errors that are witnessed at the
BIOS level.  Errors at the BIOS level are usually due to ECC failure after
all retries have been exhausted.  If the system does not setup retries, as
per the AT specs, then an immediate failure will be reported by the 2372
after only one ECC pass on the defective data.
3) If you would like to take our data separator and bench test it off of the
controller, you will find it meets the specs.  In meeting the specs it does
a better job than the comparable specs for the WD data separator.

I will not challenge the performance differences as I haven't tested them
out, but as far as the rest of your claims, they are full of hot air.  If
you would like to discuss this further, then E-mail me, as I think this kind
of talk is more bandwidth waste than anything else.  Oh, by the way, to let
you know, I have about 10 years of mass storage evaluation experience.

			Roy Neese
			Adaptec Central Field Applications Engineer
			UUCP @ {texbell,attctc}!cpe!adaptex!neese

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