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Date:      Mon, 26 Oct 2009 05:48:16 -0600 (MDT)
From:      "M. Warner Losh" <imp@bsdimp.com>
To:        hselasky@c2i.net
Cc:        hackers@FreeBSD.org, non@ever.sanda.gr.jp, freebsd-usb@FreeBSD.org
Subject:   Re: Help troubleshooting...
Message-ID:  <20091026.054816.1631944692.imp@bsdimp.com>
In-Reply-To: <200910260959.20772.hselasky@c2i.net>
References:  <20091025.133437.-1844000782.imp@bsdimp.com> <4AE4E7AF.8060103@ever.sanda.gr.jp> <200910260959.20772.hselasky@c2i.net>

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In message: <200910260959.20772.hselasky@c2i.net>
            Hans Petter Selasky <hselasky@c2i.net> writes:
: On Monday 26 October 2009 01:05:03 non@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.

Warner



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