Help troubleshooting...

[Hans Petter Selasky]

On Monday 26 October 2009 12:48:16 M. Warner Losh wrote:
> In message: <200910260959.20772.hselasky at c2i.net>
>
>             Hans Petter Selasky <hselasky at c2i.net> writes:
> : On Monday 26 October 2009 01:05:03 non at ever.sanda.gr.jp wrote:
> : > M. Warner Losh wrote:
> : > > I have a usb stick (8GB) on it.  This stick has about 5GB of junk on
> : > > it at this point.
> : > >
> : > > I tried to do 'cat * > /dev/null' recently, to measure how fast it
> : > > goes.  It got about 1GB into the drive and then I got device missing
> : > > messages.
> : > >
> : > > So devfs thinks the device went missing:
> : >
> : > Warner-san, maybe it is caused by the hardware problem on the USB flash
> : > memory. Some chip on the memory might have too much heat when you
> : > access the memory at fast rate. Then it stops working.
> :
> : What happens if you read from two USB disks at the same time?
>
> I know that the august 25th version failed badly when I tried to burn
> DVDs from a USB drive to a USB attached DVD burner.  This used to work
> flawlessly.
>
> : If the device went missing the USB HUB signalled that. This is maybe an
> : indication that the USB firmware on the device crashed. Maybe this is due
> : to heat, or unhandled race conditions when the load goes high.
>
> This same flash drive will do 20MB sustained on windows without a
> glitch using similar commands.
>
> : Try using "dd" and vary the block size from 512 to 65536 bytes. Does it
> : stop working with all block sizes over time?
>
> Once I get the message I posted, it is lights out for da0.  No further
> access to the drive works at all.
>

Make sure your driver has got sufficiently enough power, if powered over USB.

--HPS