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Date: Wed, 27 May 2009 21:30:19 +0200 (CEST)
From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
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Cc: Andrew Gould <andrewlylegould@gmail.com>
Subject: Re: interrupt storm on irq 10
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> My source of interrupt storms was caused by a bad SATA cable. Installed
> a new VIA 6421-based SATA card (selected because it was only $15) and
> two new hard drives for the purpose of copying files off two older
> drives. New drives were detected but ad4 did not work when ad6 did.
> Swapped drives and the other drive on ad6 worked. Thought the card was
> bad but decided to try swapping cables which fixed ad4 and broke ad6.
> Ergo, bad cable.
>
anyway very strange controller reaction to that case. i can hardly believe 
the way cable have to be broken to produce interrupt storm.

maybe this way:

controller sends message to drive, bad cable causes CRC errors, hard 
drive reacts with some message for that, interrupt is generated, driver in 
case of detected transmission problem instantly resends last commands, 
situation repeats.

But it's contrary to what you said that "interrupt storm" are lots of 
interrupts that are not serviced by any driver.

I'm not telling that you are wrong that cable produced this, but i can't 
find any explanation for that.

any idea?