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Re: ext3 and secure deletion of files and file slack



On Nov 09, 2002  13:42 -0500, Skylar Thompson wrote:
> On the wipe website, this caveat is mentioned:
> 
> 3. you're wiping a file in a log structured file system or
> any FS that doesn't overwrite the file's previously allocated
> sectors or the drive has reassigned one or more sectors due to error
> 
> I'm not an expert on filesystems, but "log structured file system" sounds
> like a journaled filesystem, so I'm not confident that wipe will work on
> Ext3. Another utility for deleting securely, shred, says that it is very
> difficult to delete securely on a journaled filesystem.

No, "log structured" filesystems are different than journaled
filesystems.  A log structured filesystem, like "Tux 2" or reiser4 will
not overwrite any part of an old file, but rather allocate blocks in a
free part of the disk and write the new data there before marking the
old disk blocks free.  That makes it difficult to overwrite files as you
delete them and instead you have to go with an "overwrite all the free
parts of the disk" kind of system.

For journaled filesystems, you might still "worry" a bit about data in
the journal (if using data=journal mode, or in other rare cases), but
the journal is constantly being overwritten so it is usually not a big
issue.

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/





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