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Re: Strange things happen when reading from

On Thu, Mar 08, 2001 at 03:03:53PM +0100, Christoph Groth wrote:
> Hello all,
> My box is a PC with an EPoX 8KTA2 and a Duron 700, a Matrox Millennium
> II PCI and a Gravius Ultrasound PnP (ISA).  It is running Debian 2.2r2
> (Kernel 2.2.17).
> The IDE-Devices connected to it are:
> hda: Traxdata CDRW2260+, ATAPI CDROM drive
> hdc: IBM-DTLA-307030, ATA DISK drive
> hdd: SAMSUNG WU32163A (2.16GB), ATA DISK drive

You have a rather strange drive configuration.  I'd normally put the
hard drives on the primary IDE interface, and load my CD-ROM's on the
second.  I guess it really doesn't matter, but it's just common
practice.  Also, if I'm reading it correctly, you have a nice, fast IBM
30GB drive paired with an old, slow Samsung 2GB drive.  I'd dump the
Samsung like a bad habit.  It's probably slowing down your entire IDE
channel everytime you access it.

> I am quite happy with this machine except for one thing:
> Whenever the CD-drives are accessed in some way (reading, burning) at
> least two strange effects happen:
> 1) Sound played at 44kHz becomes noisy and literally slows down.
>    Sound played at 22kHz or less isn't affected.
> 2) When connected to an ISP with the 56k external serial modem,
>    massive communication problems appear.  E.g. ping doesn't work (it
>    simply ceases to produce any output).  As soon as the CD-ROM access
>    stops, everything works again.

Have you tried removing the CD Audio cable?  I doubt it will make a
difference, but it's one more thing out of the equation.  Have you tried
using your drives seperatly?  Boot up the system with only one CD
attached and see what happens, then try it with the other.

Also, it seems as though you may be experiencing some electrical noise
problems, since both of these problems deal with very sensitive
frequencies.  Have you tried another power supply?

> Maybe changing the PIO-/DMA-Mode could help, but I don't know how to
> set them for CD-ROM drives (hdparm is only for HDDs).

You can usually set your drives for PIO mode in the BIOS, or at the very
least turn off bus-mastering for that channel.

I know I'm just offering stabs in the dark here, but it's a very strange
problem.  I don't know what tools, extra parts, or knowledge you have at
your disposal, but I'd do a part-by-part swap out until the I found the
problem.  I'd also try it under another OS on a spare hard drive.

Good luck!
Steven Dickenson	<steven@usermail.com>

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