Adaptec 2372 Controller on 386/ix

[Rick Richardson]

In article <4796 at bigtex.uucp> james at bigtex.UUCP (James Van Artsdalen) writes:
>IN article <865 at altger.UUCP>, dirk at altger.UUCP (dirk) wrote:
>> Does anybody out there have any suggestion how to use
>> the WD1006 (RLL, 1:1) Controller under 386/ix or 386/V ?

>> I found out that Interleave 6 is the fastest one, but it is
>> slower than using a regular WD1003 with interleave 2.

>This makes little sense to me: this is a *1:1 interleave* controller:
>you should use 1:1 interleave.  If the controller buffers by reading
>an entire track at a time, formatting with 6:1 interleave could really
>slow things down if the controller isn't smart enough to read the
>sectors as they come (and I think the WD1006 might be this dumb - if
>not, then your chosen interleave would be entirely irrelevant).

I installed an Adaptek 2372 RLL controller under 386/ix.  This controller
is supposed to be 1:1.  I think that the AMI BIOS even suggested that
the best interleave (empirically determined) would be 1:1.  The drive
is a Miniscribe 6128.

However, I formatted and loaded 386/ix with both 1:1 and 3:1 (the default),
interleaves, and 3:1 was faster.  I didn't have time to investigate
further into the apparent discrepancy, like trying 2:1.  It seems clear,
though, that the 2372 does NOT buffer an entire track at a time, as soon
as it starts seeing the sectors for that track.
If it did, like James says, the interleave factor would make only a minor
difference.  I'd guess that Adaptek means that the 2372 is capable of
1:1 interleave on a wet day in North Dakota :-).  386/ix could have
provided better support for pseudo 1:1 controllers in the disk driver
itself.

I'm pretty happy with the improved storage capacity, and the disk plus
controller cost only $930, for about $8.50/megabyte.  Still, I think
that the "1:1 interleave" claim falls into the same class as "zero
wait-state" -- you have to read the fine print in order to conclude
that these things are really achievable in "Real World" operation.
I take the blame on myself for fully investigating the zero wait
state issue, but blindly believing in 1:1 interleave claims.
-- 
		Rick Richardson, PC Research, Inc.

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