small question about tape-based dumps

[Stevan Tiefert]

Am Freitag, den 16.10.2009, 17:37 -0400 schrieb Jerry McAllister:
> On Fri, Oct 16, 2009 at 11:13:21PM +0200, Stevan Tiefert wrote:
> 
> > Hello list,
> > 
> > one example: If I have three partitions and I want to backup every day
> > these partitions, will I need 21 tapes?
> > 
> > I ask because it seems it is not possible to place more than one dump on
> > one tape, isn't it?
> 
> You can easily put more than one dump on a tape if there is
> room enough for them.   Check out the  mt(1)  command.
> 
> Something like   mt fsf 1    will skip over the first dump file
> so you can write the second.    mt fsf 2   will skip over two files, etc.
> That is dump files, not files within the dump.   Each dump of a
> filesystem is one file.  
> 
> If you need to restore, it is just the same.   The first dump is
> the first file.  The second dump is reached by skipping 1 file
> with the mt command, etc.
> 
> I actually rewind and skip between each dump of multiples made
> to the same tape.   I also use the no-rewind device for the tape.
> 
> So first dump is:    dump 0af /dev/nsa0 /
> 
> For second dump:     mt -f /dev/nsa0 rewind
>                      mt -f /dev/nsa0 fsf 1
>                      dump 0af /dev/nsa0 /usr
> 
> third                mt -f /dev/nsa0 rewind
>                      mt -f /dev/nsa0 fsf 2
>                      dump 0af /dev/nsa0 /var
> 
> etc.
> 
> when all done        mt -f /dev/nsa0 rewind
>                      mt -f /dev/nsa0 offline
> 
> I have this all in a script that also writes an index file
> as the first file on the tape.     
> 
> Of course if you are doing a change dump the dump command is
> going to look more like:
> 
>                      dump 1af /dev/nsa0
> etc.
> 
> ////jerry    
>   
> > 
> > With regards
> > Stevan Tiefert
> > 
> > 
> > 
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Hello Jerry,

The world can be so easy!!! Thanks for this hint :-)

With regards
Stevan Tiefert