Deleted Files

Jim Herrmann kclug at ItDepends.com
Tue Jun 8 03:17:13 CDT 2004


I found this in the e2undel readme, and my heart sank.  Is there anybody 
out there who can help me undelete?  My wife has said she'll pay 
someone.  What is lost is all her mail files.  I have a very very old 
backup, from a long time ago.  That just won't do.  I REALLY need to 
find the data on the disk.  I have pulled the disk from the machine so 
that nothing further happens to it whilst I research what I can do. 

Thanks for any help.  Here's the bit from e2undel:

What happens if you delete a file?
-----------------------------------

If you delete a file stored on an ext2 file system, its data is not 
instantly lost. What happens is:

- ext2 marks the file's data blocks as avalaible in its block bitmap

- ext2 marks the file's inode as available in its inode bitmap

- ext2 sets the deletion time in the file's inode

- ext2 invalidates the file's name in the directory entry

So, the file's data is not actually deleted (but it might be overwritten 
in the future); and the crucial information in the inode (owner, access 
rights, size, data blocks occupied by the file and some more) is not 
touched. If you know the inode number, you can recover the file by using 
Ted Ts'o's debugfs tool.

What is lost however is the association between the file name and the 
inode: You can't restore the former file name from the inode 
information. To recover the data of a deleted file, you must completely 
rely on the information in the inode like file size, owner, deletion 
time, etc.

ext3 behaves different from ext2 in one regard: When a file is deleted, 
the information in the inode is also removed. Tools like e2undel (or Ted 
T'so's debugfs) that rely on this information when undeleting files 
don't work anymore.

It's this last paragraph that kills me!  I may be screwed!  Help!




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