Occasionally the topic arises about what to do when a file is
corrupted. ZFS will tell you about it, but what then? Usually
the conversation then degenerates into how some people can
tolerate broken mp3 files or whatever.
Well, the other day I found a corrupted file which gave me an
opportunity to test a little hypothesis on how to recover what
you can recover. Details are in my blog:
http://blogs.sun.com/relling/entry/holy_smokes_a_holey_file
There is an opportunity here, for someone with some spare time,
to come up with a more clever solution than my dd script. hint...
hint...
-- richard
Hi Richard, Richard Elling wrote:> Occasionally the topic arises about what to do when a file is > corrupted. ZFS will tell you about it, but what then? Usually > the conversation then degenerates into how some people can > tolerate broken mp3 files or whatever. > > Well, the other day I found a corrupted file which gave me an > opportunity to test a little hypothesis on how to recover what > you can recover. Details are in my blog: > http://blogs.sun.com/relling/entry/holy_smokes_a_holey_file > > There is an opportunity here, for someone with some spare time, > to come up with a more clever solution than my dd script. hint... > hint... > -- richard > >Would it help if you had the block number (i.e., disk location) of the block that is corrupted? zdb might tell you this. I have a way to do it, I think, but don''t want to test it because I don''t want to corrupt a file on purpose. I am writing a paper (actually, done with first draft) that allows you to find the data for a given file on the raw disk (i.e., file system is not mounted). I plan on presenting this at osdevcon in Prague in June. I am looking for reviewers. If you are interested, please send me email and I''ll send you a copy. The method I use is quite a bit more complex than using dd. It involves using a modified zdb and modified mdb together. I think it would work for this type of problem. (Then again, if zfs completely wipes out the corrupted block, it won''t help). If I have time, I''ll try corrupting a few bits in a file and see if my method works to get the corrupted block. thanks, max> _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > >
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Richard Elling wrote: | Well, the other day I found a corrupted file which gave me an | opportunity to test a little hypothesis on how to recover what | you can recover. Details are in my blog: | http://blogs.sun.com/relling/entry/holy_smokes_a_holey_file | | There is an opportunity here, for someone with some spare time, | to come up with a more clever solution than my dd script. hint... | hint... dd_rescue: http://www.garloff.de/kurt/linux/ddrescue/ - -- Jesus Cea Avion _/_/ _/_/_/ _/_/_/ jcea at argo.es http://www.argo.es/~jcea/ _/_/ _/_/ _/_/ _/_/ _/_/ jabber / xmpp:jcea at jabber.org _/_/ _/_/ _/_/_/_/_/ ~ _/_/ _/_/ _/_/ _/_/ _/_/ "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ "El amor es poner tu felicidad en la felicidad de otro" - Leibniz -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iQCVAwUBR9tJiplgi5GaxT1NAQJJ6gP/a9zy6rBfRREzw1aXCF6JX17O/DVDEPY5 3aFr1NbBuH1CDrSwSidjMKf44JkERZ3b9GmamQ+qf+mqnofVF8ynducIcYUty6og uj0Zsiz3RGj1yK+p6DUbye2FiE8v3GA8U2mITC1Luz/zeTvWeDCIkT65VspTpw7s mqBKsKqyo+I=F6fz -----END PGP SIGNATURE-----