On Tue, Jul 19, 2005 at 05:53:00PM +0200, Michael Weiser wrote:
> On Mon, Jul 18, 2005 at 04:01:25PM -0400, Jon LaBadie wrote:
> 
> > > > The amrestore command is getting the file in uncompressed format
> > > > even if it was compressed.  If you want to transfer the compressed
> > > > form I think you could add the -r option.
> > > I think it's -c actually and the manpage is a bit ambiguous on the
> > > actual workings it. From the phrasing I'd expect the files to be
> > > uncompressed if necessary and then recompressed if requested using -c.
> > > That would mean processing the whole archive twice - first uncompressing
> > > then recompressing.
> > It also says the -r options causes the output to be exactly as on "tape".
> > Thus it 'should' avoid the double processing.
> 
> Right. But ;) it goes on to say that this also includes amdump headers.
> What good would that do? I wouldn't be able to extract it using the
> original archive/dump program, would I?

        dd if=/dev/stdin of=stdout bs=32k skip=1


> 
> Ah, but that closes the circle: I wanted to know how to extract stuff
> from virtual tapes using amrestore in the first place. Once I know that
> I'm quite happy to do amrestore -p | ssh box cat/tar/whatever.
> 
> But you peeked my interest: How do I feed the raw amdump file to
> amrecover to extract individual files on the client? Wouldn't it need
> the index from the server? I'm confused. ;)
> 
> Ah, reading the man page and RTFMing the documentation helps a bit - I

Oh my gosh, now there is an idea, RTM ;))


> That, of course, would be a viable alternative to extracting the
> archives using amrestore. But how efficient/fast is that for whole disks?

Never timed it, but a WAG is that it would be similar.  The actual commands
executing are the same except for the network transfer piece.

One thing to consider is that amrecover would restore to the state as of
a particular date.  It would take the virtual tapes and dump files in
the corrrect order.  Also, if the date you pick the restoration point
was an incremental, I believe files deleted between the level 0 and the
incremental will also be deleted in your amrecover'ed result.  These
things would have to be done by humans with amrestore.

> The documentation on www.amanda.org seems to focus on amrestore for
> whole disks and advertises amrecover for individual files.

As is appropriate!  Your OP questioned the possibility of amrecover
for the purpose, thus my comments.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
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