On Mon, 2006-04-17 at 16:01 -0400, Jon LaBadie wrote:
> On Mon, Apr 17, 2006 at 01:35:04PM -0600, Tom Schutter wrote:
> > I was wondering if anyone can tell be the best way to duplicate an
> > Amanda tape on a Linux box.  I will have two identical tape drives.  I
> > would much prefer to use standard UNIX commands.  The program "tcopy"
> > would be perfect, but it is not available on Debian, it a google search
> > indicates that is has problems.
> > I would think that "dd" could do the trick, but what is the correct
> > incantation?
> > 
> 
> tcopy was going to be my suggestion until you said you were
> not using Solaris :(  Is tcopy available on any other OS?
> 
> If you know the tape block size (amanda's is 32K) then
> I think it would be:
> 
>       dd bs=32k if=/dev/<xxx> of=/dev/<yyy>
> 
> where xxx are the no compression devices or with compression
> turned off.
> 
> As I type this I realize that dd will only copy the first
> tape file.  So this will have to loop.  And you will need
> to use the no-rewind device.  So something like:
> 
>       $ mt -f /dev/n<xxx> rewind
>       $ mt -f /dev/n<yyy> rewind
> 
>       $ while dd bs=32k if=/dev/n<xxx> of=/dev/n<yyy>
>       > do
>       >       :       # a colon == no-op command
>       > done
> 
> dd returns 0 on successful copy, non-zero on failure.
> The loop should terminate when the input fails at EOT.

Perfect, just what I needed.  For the archives, a slight improvement (so
the command is easier to repeat):
  while dd bs=32k if=/dev/n<xxx> of=/dev/n<yyy> ; do : ; done
-- 
Tom Schutter (mailto:tom AT platte DOT com)
Platte River Associates, Inc. (http://www.platte.com)