[Bug-tar] Incremental restore problem

[Daniel Haude]

Hello list,

I browsed a bit through the archives but couldn't find any info on this.

Short question: What happens if a file is moved (but otherwise not  
touched) before an incremental backup? It seems that listed-incremental  
goes only by inode, not by file location, and therefore the file gets lost  
upon restore.

Here's what happened: For a while I've been running daily  
listed-incremental backups of my home dir. Just for testing purposes I did  
an incremental extract into another dir and compared with the actual  
contents of my home dir. To my surprise I found dozens of files missing in  
one particular directory tree. The directores were all there but empty.  
That directory tree had been created a few days ago during a  
reorganization of my files, and most of it contents had been moved there  
from other locations.

At first I thought that something must have gone wrong during the backup  
on the day when I moved all the stuff, but then I noticed that only the  
moved files were missing but not those that had been newly created or  
modified. It seems that tar just goes through a list of inodes, backing up  
those that have changed, but forgetting about those that have been moved  
to different locations unchanged.

Of course if worst came to worst the actual data could still be restored  
from earlier backups, but sometimes you don't really know what you're  
looking for or you forgot a file's name, and then what?

Reading through the mailing lists I got the impression that the  
incremental restore is supposed to generate a 100% accurate replica of the  
original directory structure. In that case the behavior in case of moved  
files should be considerered.

I'm using tar 1.14 of Debian stable. I just saw it is copyrighted back in  
2004. Maybe there is a newer version where this behavior has been fixed.  
I'll look.

Regards, --Daniel