On Thu, Jun 10, 2010 at 12:20:39PM -0700, David Mathog wrote: > Jesse Becker and others suggested: > > > http://users.softlab.ntua.gr/~ttsiod/rsbep.html > > I tried it and it works, mostly, but definitely has some warts. > > To start with I gave it a negative control - a file so badly corrupted > it should NOT have been able to recover it. > > % ssh remotePC 'dd if=/dev/sda1 bs=8192' >img.orig > % cat img.orig | bzip2 >img.bz2.orig > % cat img.bz2.orig | rsbep > img.bz2.rsbep > % cat img.bz2.rsbep | pockmark -maxgap 100000 -maxrun 10000 > >img.bz2.rsbep.pox > % cat img.bz2.rsbep.pox | rsbep -d -v >img.bz2.restored > rsbep: number of corrected failures : 9725096 > rsbep: number of uncorrectable blocks : 0 > > img.orig is a Windows XP partition with all empty space filled with > 0x0 bytes. That is then compressed with bzip2, then run > through rsbep (the one from the link above), then corrupted > with pockmark. Pockmark is my own little concoction, when used as > shown it stamps 0x0 bytes starting randomly every (1-MAXGAP) bytes, for > a run of (1-MAXRUN). In both cases the gap and run length are chosen at > random from those ranges for each new gap/run.
The website is more interested in corrupted block media, with the assumption said corruption manifests as a cluster of invalid blocks from the file. You've got a different type of corruption. > % cat img.bz2.rsbep | pockmark -maxgap 1000000 -maxrun 10000 > >img.bz2.rsbep.pox2 > % cat img.bz2.rsbep.pox2 | rsbep -d -v >img.bz2.restored2 > rsbep: number of corrected failures : 46025036 > rsbep: number of uncorrectable blocks : 0 > % bunzip2 img.bz2.restored2 > bunzip2: Can't guess original name for img.bz2.restored2 -- using > img.bz2.restored2.out > bunzip2: img.bz2.restored2: trailing garbage after EOF ignored > % md5sum img.bz2.restored2.out img.orig > 7fbaec7143c3a17a31295a803641aa3c img.bz2.restored2.out > 7fbaec7143c3a17a31295a803641aa3c img.orig He documents a "freeze.sh" and "melt.sh" (in the contrib dir) that wrap rsbep and rsbep_chopper. That's very different from what you did. [...@closter ~]$ ls -l junk.avi -rw-rw-r-- 1 dnl dnl 12622344 2010-02-28 19:17 junk.avi [...@closter ~]$ freeze junk.avi > freeze1 [...@closter ~]$ melt freeze1 > melt1 [...@closter ~]$ md5sum freeze1 junk.avi melt1 4f8052c358e5bd86b9bfffd980726940 junk.avi dcbeafa75ec60f50d003876866009213 freeze1 4f8052c358e5bd86b9bfffd980726940 melt1 [...@closter ~]$ ls -l junk.avi freeze1 melt1 -rw-rw-r-- 1 dnl dnl 14565600 2010-06-10 14:56 freeze1 -rw-rw-r-- 1 dnl dnl 12622344 2010-02-28 19:17 junk.avi -rw-rw-r-- 1 dnl dnl 12622344 2010-06-10 14:56 melt1 [...@closter ~]$ The above only shows a single example of it not damaging an intact file. But I only played with it for about 10m last night and the above is a laugh test. I'll start proper testing tonight... -- David N. Lombard, Intel, Irvine, CA I do not speak for Intel Corporation; all comments are strictly my own. _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
