Kevin Brosius on 24 Apr 2005 23:15:15 -0000

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Re: [PLUG] USB Mass storage question

Doug wrote:
> I have an external USB mass storage drive running under SUSE 7.3 (an ATA
> drive in an external USB box).
> What is the correct way to disconnect this drive. When I unmount
> everything and shutdown the power I get a kernel message that it lost the
> controller and something about that being "very bad."

> Ok the supposed bad message (turning power off) is:
> Apr 22 22:47:13 bridget kernel: uhci: host controller halted. very bad
> Apr 22 22:47:13 bridget kernel: usb.c: USB disconnect on device 2

So, you see these in the log the next time you power the system up? 
This is not really a concern, as Stephen says.  It just indicates that
the driver author never expected the USB host controller in your
computer to halt.  This isn't a big deal.  I'd be more concerned about
the file system on your external device.  How do you mount the device? 
usbfs or such?  Then I wouldn't worry.

> When I just disconnect the USB cable from the drive it seems to be a more
> benign message that it was disconnected.
> I would like to leave this drive installed (USB connected) and just turn
> off the power when it is not in use. I use it as a backup. Is there a
> better way to do this?

Or did you mean you turn off the power to the external drive only and
not the system?  That should not cause the local USB host controller to
halt.  It sounds like a bug in the uhci driver, unless the drive does
something really bad on the USB bus.  It still shouldn't halt the
controller, but I've run into bad controller hardware before, and you
may not be able to do anything about that without swapping your USB

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