Date: Wed, 26 Feb 2014 14:55:27 +0100 From: Polytropon <freebsd@edvax.de> To: Matthias Apitz <guru@unixarea.de> Cc: freebsd-questions@freebsd.org Subject: Re: errors from external USB disk Message-ID: <20140226145527.3cd8eb4b.freebsd@edvax.de> In-Reply-To: <20140226121714.GA1532@tiny-r255948> References: <20140226121714.GA1532@tiny-r255948>
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On Wed, 26 Feb 2014 13:17:14 +0100, Matthias Apitz wrote: > Sometimes, after the dump finished, a re-read of the file to get the MD5 > checksum results in errors and I was highly concerned about the integrity > of my dumps on this device. What error? Can you post the error message and the command which caused it? > I bought another 2.5 TB disk and was able to copy all the files (around > 1TB) over, i.e. the device could now be owerwritte while testing. > > What is the best way to run a test on the disk? I'm thinking in > something like reading/writing the block in place for many days > (it's around 1.5 TB). Any ideas? You can start by looking at the S.M.A.R.T. data (sysutils/smartmontools and sysutils/smartcontrol), see "man smartctl" for "smartctl -a". This should help you to identify possible hardware errors. If the disk is connected to USB, data _could_ be "lost" on that way, too. Still it seems that your file system on disk is not damaged (check with fsck -f /dev/da1s1a in umounted state). The backup file should be entirely readable. You can copy or dd it to /dev/null to make sure the entire file is being read. Providing error messages could help to diagnose this further. At the moment I'm just guessing. :-) -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...
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