ez-scsi speed settings and aic7890

[Dennis J.A. Bijwaard]

Mike Bilow wrote:
>  DL> There is nothing wrong with that configuration.  The problem
>  DL> appears to be memory corruption.  When the CD-ROM is run at
>  DL> full speed under NT along side the Ultra2 disk, you get
>  DL> corruption as well.  Because the linux ext2 filesystem is in
>  DL> general faster than NT's filesystem, you see the same memory
>  DL> corruption with lower speeds on the CD-ROM.  Basically,
>  DL> linux is faster and that makes it break with lower transfer
>  DL> speeds.  I would suggest you try swapping out the RAM and/or
>  DL> CPU to see if the problem goes away.

Shouldn't I notice any other corruption when the memory or processor
is at fault?

I compiled a lot, kernels/kde-1.1/wine etc which I downloaded by cable
from the internet. But the programs all seem to run as expected.

I also tried 5Mb/s asynchronous on the aic7890 in linux, with the same
problems.
> 
> I would like to take a flyer on this one, but I disagree with Doug's guess
> about memory corruption.  I agree that the driver is not at fault, of course.
> 
So do I, but I could do with some extra ram. This will give me the
change to 
rule out this possibility, or get a replacement from the company where I
bought
the whole bunch.

> My guess is that the CD-ROM drive is bad.  Running in the presence of an 80MB/s
> Ultra2 device might confuse it.  If you can, I suggest that swapping the CD-ROM
> drive with, frankly, a better brand -- say, Toshiba -- might solve your
> problem.  I would go so far as to say that, in my opinion, it is unlikely that
> Doug's suggestion about swapping RAM and CPU will have any effect.

Well Mike, let me tell you a secret. The same problem occurs on the
ricoh drive
when I read/compare an iso image on the aic7890. I did not test this
often because
the drive only supports 4 speed :-(

> You could probably stabilize the system by limiting the hard drive data rate,
> but that is not a real solution.  Overterminating the SCSI bus, so that
> termination on the controller (which must be in the middle on your system) is
> enabled in addition to each end of the bus could help, too, although this is
> certainly not a recommended long term solution.

This seems a bit farfetched in my opinion. But thanks for the
suggestion.

-- 
Kind regards,
			Dennis Bijwaard


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