Re: GNU tar fails to restore listed-incremental backup

[Joerg Schilling]

Deweloper <address@hidden> wrote:

> I'm using GNU tar for incremental backup using --listed-incremental
> option. Unfortunately there seems to be a problem with restoring such
> backup if following operations are performed:
> 1. Rename directory d1 to d3
> 2. Rename directory d2 to d1
> Backup created afterwards contains:
>
> R./d2 T./d1
> R./d1 T./d3
> R./d2 T./d1
>
> Restoring it fails with:
>
> tar: Cannot rename './d2' to './d1': Directory not empty
> tar: Exiting with failure status due to previous errors

This bug exists since that "incremental feature" has been first announced for
GNU tar in ~ 1992.

The bug has been reported at least 4 times since September 2004 and it will 
probably never be fixed as this is a problem that results from the basic 
concept for incremental dumps used in GNU tar. So it is impossible to make it 
working without introducing a completely new and different incremental 
system comcept... 

I recommend you to use star that has been verified for being able to correctly 
restore incremental star dumps thousands and thousands of times with real 
world's data.

You of course need to use star for your backups as well, as star uses a 
different concept for incrementals that was derived from the definitely working 
concept in ufsdump/ufsrestore from BSD Unix from 1981.

Check: http://schilytools.sourceforge.net/man/man1/star.1.html

Incremental dumps are explained starting from approx. page 53

BTW: Incrementals made with star are also smaller than incrementals made with 
gtar.

Jörg

-- 
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