Date: Fri, 28 Feb 2014 07:05:37 +0100 From: Matthias Apitz <guru@unixarea.de> To: kpneal@pobox.com Cc: Polytropon <freebsd@edvax.de>, freebsd-questions@freebsd.org Subject: Re: errors from external USB disk Message-ID: <20140228060536.GA5281@La-Habana> In-Reply-To: <20140227191930.GA48451@neutralgood.org> References: <20140226121714.GA1532@tiny-r255948> <20140226145527.3cd8eb4b.freebsd@edvax.de> <20140227115934.GA2006@La-Habana> <20140227150715.e6aa0594.freebsd@edvax.de> <20140227175258.GA3214@La-Habana> <20140227183248.GA3339@La-Habana> <20140227191930.GA48451@neutralgood.org>
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El día Thursday, February 27, 2014 a las 02:19:30PM -0500, kpneal@pobox.com escribió: > > The bad block is there; if I restart the reading from 10 blocks before this > > point, it stops at the same block: > > > > # dd if=/dev/da0 of=/dev/null bs=1m skip=712860 > > dd: /dev/da0: Input/output error > > 10+0 records in > > 10+0 records out > > 10485760 bytes transferred in 4.017767 secs (2609848 bytes/sec) > > Bad blocks are supposed to be mapped out when rewritten. > > Having said that, I used to run an external drive through a USB hub. I > ended up with silent, random corruption. I haven't seen any corruption > since I removed the hub, but now I don't trust USB with my data. I have now read the entire disk with dd(1) and the bad area is only in one are, between the are 712870 ... 712874 (based on bs=1m). I rewrote this area with # dd if=/dev/zero of=/dev/da0 bs=1m oseek=712870 count=4 4+0 records in 4+0 records out 4194304 bytes transferred in 0.987089 secs (4249165 bytes/sec) and now the area can be read fine: # dd if=/dev/da0 of=/dev/null bs=1m skip=712869 count=10 10+0 records in 10+0 records out I will now ree-read the entire disk with dd(1) and will overwrite after this entire disk from /dev/zero. Thx matthias -- Matthias Apitz | /"\ ASCII Ribbon Campaign: www.asciiribbon.org E-mail: guru@unixarea.de | \ / - No HTML/RTF in E-mail WWW: http://www.unixarea.de/ | X - No proprietary attachments phone: +49-170-4527211 | / \ - Respect for open standards
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