problems with AHCI on FreeBSD 8.2

John john at
Thu Feb 16 05:05:58 UTC 2012

Jeremy Chadwick wrote:
> CRC errors ...
>I have no real advice for tracking this kind of problem down.  The most
>common response is "replace cables", which isn't necessarily the root
>cause.  I have no advice or tips on how to track down interference
>issues, or how to truly examine a disk PCB or controller PCB for the
>latter item.  "Flaky traces" on a PCB could cause this sort of thing.
>Folks in the EE field would know more about these issues; I am not an EE
>Since the attribute increased on both drives simultaneously (I have to
>assume simultaneously?), it's more likely that the problem is not with
>SATA cables or the drives but the controller on the motherboard.  I'd
>recommend replacing the motherboard.  I make no guarantees this will fix
>anything however, but it is the "common point" for both of your drives.

This EE agrees with your advise. I would add if replacing the motherboard fails
to fix the problem, then replace the power supply. Even with extremely high
end test equipment, you likely would never be able to see the failure occur
for at least two reasons; the most likely failure mode is inside a single IC,
and adding probes would alter the environment enough to change the failure

John Theus
TheUs Group

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