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Date: Mon, 09 May 2005 14:07:32 -0400
To: Chris Fedde <chris@fedde.littleton.co.us>,
	freebsd-questions@freebsd.org
From: WMC <wc_fbsd@xxiii.com>
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Subject: Re: swap space problems
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At 01:20 PM 5/9/2005, Chris Fedde wrote:
>Occasionaly my system hangs for a few seconds while loading a process
>from swap that has been idle for some time.
>     ad0: TIMEOUT - WRITE_DMA retrying (2 retries left) LBA=161663

What type of driver interface and controller is this?  And what FBSD version?

I used to get this error when I was trying to get a SATA drive working last 
summer.  There were bugs in the ata driver (circa 5.2.1) that are about 96% 
fixed in 5.3.  It would happen under heavy disk IO doing a lot of random 
seeks.  The hang really is a hang, not just a delay from the swapping 
activity.  40 or 50% of the time, it resulted in a "hard" full system hang 
(ie:  had to power cycle or hit the reset button.)  Often there was severe 
data corruption, also.

   -Wayne