Xref: utzoo comp.sys.amiga:24213 comp.sys.amiga.tech:2182
Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!batcomputer!itsgw!steinmetz!rocky!perley
From: perley@rocky.steinmetz (Donald P Perley)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Re: Hard Disk Performance tests, comments invited
Message-ID: <12391@steinmetz.ge.com>
Date: 20 Oct 88 17:38:32 GMT
References: <10150@cup.portal.com>
Sender: news@steinmetz.ge.com
Reply-To: perley@rocky.steinmetz.ge.com (Donald P Perley)
Distribution: na
Organization: General Electric CRD, Schenectady, NY
Lines: 56

In article <10150@cup.portal.com> thad@cup.portal.com (Thad Thad Floryan) writes:
>Following are some most-interesting disk performance results.

>   	The object of the comparisons are to show that "True DMA" controllers 
>     are not always the best.  In fact, the fastest times were obtained using
>     boards that use no DMA,  instead using polled I/O to read/write data.
>     These were early tests and are not the fastest times obtained.
>     These tests show the difference between the non DMA boards and DMA boards,

 > ............ a bunch of benchmarks ...............

These show good data rates... GREAT!

As comparisons between DMA and non-DMA, they show that:


	non-DMA is faster than DMA

	OR

	Quantum pro-drives are faster than Seagate ST251-1 or Miniscribe
	3053.

	OR
	
	SCSI is faster than ST506

	OR

	The 2090 design is lacking in some other respect.




Somehow, with all those variables involved, dma/non-dma doesn't jump
out as the clear explanation. 

If this is suposed to compare DMA to non-DMA, it would make sense to
use the same disk drive for both cases.  Apparently they thought it
was worthwhile to move the Quantum around to all the non-dma boards...
why not put it on the 2090?



Another consideration: Even if a non-dma controller has a higher
mazimum speed, what is the impact on CPU load?



Thad's point in posting this was that FFS can give transfer rates
in the 500k/sec range, which is still valid, and I'm not trying to flame
him..... just the part about the object of the comparisons, written
by the hurricane people.


-don perley