On Mon, Jul 18, 2011 at 6:42 AM, Sandra Escandor [off-list ref] wrote:

Thanks for the insight Robert. Do you (or anyone else on the list) know
if there are any utilities that exist that would be able to allow me to
observe (and log) the power consumption of the drives during high I/O?

I don't think there's anything that you could do to measure this in
software. A clamp-on ammeter on one of the power supply wires would
give you a measurement, but it might not catch brief current spikes
that could be causing problems.

Usually these kinds of problems get fixed by trial and error (swapping
drives between cables, a different PSU).

-----Original Message-----
From: Robert Hancock [mailto:hancockrwd@gmail.com]
Sent: Friday, July 15, 2011 9:17 PM
To: Sandra Escandor
Cc: linux-ide@vger.kernel.org
Subject: Re: Western Digital Scorpio and ICH10R on Debian - NCQ issue?

On 07/12/2011 10:21 AM, Sandra Escandor wrote:

quoted

The Situation:
It appears that a WRITE FPDMA QUEUED failed command causes driver
timeouts - this in turn locks up the RAID (which once worked pretty
well). This occurred during high I/O.

The question:
1. Is it a good idea to turn off NCQ? I've read in different posts

that

quoted

it helps some, but not others - I'm currently on the way to getting an
experimental box setup, but I wanted to confirm if this was a good

idea.

Not really a solution to anything, at least not likely in this case.
More of a workaround that might happen to work by chance.

quoted

2. Are there known issues with the ICH10R + WD7500BPKT-00PK4T0 and the
libata driver?

Nothing known, no.

quoted

The System:
Four WDC WD7500BPKT-00PK4T0 drives (Western Digital Scorpio) - in

RAID10

quoted

array created using mdadm 3.1.4
ICH10R sata controller.
Kernel 2.6.32-5-amd64

The fact that you have multiple drives and the problem tends to occur
during heavy I/O may point to a power issue. This has been known to
happen when some of the drives aren't getting enough power when there
are spikes in power draw during I/O access. In this case, using a
beefier power supply or spreading the drives out across different cables

from the PSU may help.