On 04/11/2012 19:34, Sergey Vlasov wrote:
On Sat, Nov 03, 2012 at 09:14:08PM +0100, Miguel Dardenne wrote:
On 2012-11-03 17:50, Alan Stern wrote:
I get a USB disconnect of my external USB HDD about once per day.
Enabling USB debug in the kernel shows the first error as 'ehci_hcd
detected XactErr'. It happens only when the drive is idle. For
example,
I had a process writing on the HDD every 3 seconds and the problem
did
not occur for several weeks.
Correction: These errors do not occur when the drive is idle. You
can
see in the log you attached:
OK thanks for this. I then reformulate my statement: using the drive on
a frequent basis (3s period) prevents the problem from occuring.
Then the problem might be related to the power management in the drive
itself, not in the host OS. 2.5" drives tend to have a short spindown
timeout, and the first operation performed after such timeout causes
the drive to spin up. The spinup process consumes a lot of power
(more than during sustained operation), and current fluctuations
during this process might cause problems if any components in the
power supply chain are marginal (even a lousy cable with too thin
conductors can be problematic).
You might be able to change APM settings of the hard drive using
utilities like hdparm; however, this might not work with your
particular WD external drive for several reasons:
- Not all USB-SATA bridges can pass low-level ATA commands needed to
change APM settings. If you purchase an USB-SATA enclosure and HDD
separately, you could work around this problem by attaching the
drive to a SATA port directly to perform this configuration (APM
settings are usually persistent), but doing this with an external
USB drive sold as a single item will probably void the warranty.
Even worse, some external drives made by WD have the USB port
actually soldered to the drive PCB itself, and the SATA interface
is not accessible directly.
- WD drives often need undocumented vendor-specific commands to
control spindown (google for "wdidle" used for 3.5" WD Green
drives; not sure about their 2.5" drives). Even if the appropriate
tools exist, they might not work with USB-attached drives.
Did you try to use another drive with this system? Using a drive with
a separate power supply might at least rule out the power-related
problems. You can also try to attach the drive to a powered USB 2.0
hub instead of directly attaching to the onboard port.
Hi all,
Long story short : I bought a powered USB hub and have now had uptimes
of more than two months without any HDD disconnect.
So the issue was too high current drain from one of the disks when
coming back of idle mode, which reset the Alix board.
Hoping this will help someone.
Thanks for your support and best regards,
Miguel
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