Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1425331AbWLHKZK (ORCPT ); Fri, 8 Dec 2006 05:25:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1425332AbWLHKZK (ORCPT ); Fri, 8 Dec 2006 05:25:10 -0500 Received: from hp3.statik.TU-Cottbus.De ([141.43.120.68]:48532 "EHLO hp3.statik.tu-cottbus.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1425331AbWLHKZI (ORCPT ); Fri, 8 Dec 2006 05:25:08 -0500 Message-ID: <45793D82.1040807@s5r6.in-berlin.de> Date: Fri, 08 Dec 2006 11:25:06 +0100 From: Stefan Richter User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.0.8) Gecko/20061030 SeaMonkey/1.0.6 MIME-Version: 1.0 To: Matthias Schniedermeyer CC: Robert Hancock , linux-kernel , DervishD Subject: Re: single bit errors on files stored on USB-HDDs via USB2/usb_storage References: <4578D97F.7020107@shaw.ca> <45792B4D.8050705@citd.de> In-Reply-To: <45792B4D.8050705@citd.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1693 Lines: 40 Matthias Schniedermeyer wrote: > Robert Hancock wrote: >> Matthias Schniedermeyer wrote: >>> I have a 1,5 Meter and a 4,5 Meter cable connected to the USB-Controller >>> and i only use of them depending on where the HDD is placed in my room, >>> the other one is dangling unconnected. >>> >>> Then i will unconnect the short cable and use the long cable exclusivly >>> and see if it gets better(tm). BTW, I suspect front panel connectors could introduce noise too, via the jumper cables from motherboard to the panel. >> That long cable could be part of the problem - I don't think the USB >> specification allows for cables that long (something like a 6 foot max >> as I recall). > > http://en.wikipedia.org/wiki/USB2 > > Says that 5 meters are allowed. I don't know about USB 2.0, but in case of FireWire, ~4.5m long cables are theoretically in spec too. I've got a FireWire 400 and a FireWire 800 cable this long, and both don't work very unreliable. Depending on what's connected, they fail sooner or later. However due to how FireWire works, this is immediately noticed as data CRC errors or bus resets. I.e. it's nearly impossible for noisy hardware to _silently_ cause data corruption. I would suppose USB has similar CRC checks. Also, you mentioned that the corruption occurs systematically on certain byte patterns. Therefore it's certainly not related to the cables. -- Stefan Richter -=====-=-==- ==-- -=--- http://arcgraph.de/sr/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/