sean finney on 9 Sep 2004 02:37:01 -0000


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Re: [PLUG] Hard drive crash - recovery


hi eric,

On Wed, Sep 08, 2004 at 07:14:30PM -0400, eric@lucii.dnsalias.org wrote:
> Can anybody point me to some useful sites and/or tools for trying to
> recover this?

of course, it goes without saying it's best to assume the data is
permanently lost forever.  that way, if you do get it back, it's
a pleasant surprise :)

the first thing i would do if you can still dd off of the disk is
retry with a program called dd_rescue.  there's an option you can
pass to tell it to fill in the output with zeros blocks that were
unreadable in the input, which might be important to keep
block offsets consistant (it'll probably still corrupt some
inodes, but probably more likely to be successful).  also, when it detects
errors, it shrinks the default block size which hopefully will minimize
and isolate the unreadable areas on the disk.

that failing, in the past i've the coroner's toolkit / lazarus to
bring data back from the dead in similar situations (though this
was admittedly with ext2/3, ymmv with reiserfs).  be warned, you'll
need a lot of time and disk space for that.  in my particular
situation, i used tct/lazarus to find the blocks where the files
i wanted started, and then wrote a small c program to read the data[1].


hth
	sean


[1] for some reason, about 12 or 13 blocks into every file (and only at
    that particular offset) was a block of gobbledegook which was
    preventing lazarus from resurrecting my jpegs.

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