On Tue, Apr 27, 2004 at 10:10:40AM +0200, Hans van Zijst wrote:
> First off, I'm not an Amanda expert either, so maybe I'm talking rubbish 
> here. If so, I'm sure someone will correct me :)

I guess that would be me...

> AFAIK you can't use the same tape for several consecutive backup sessions. 
> Amanda uses its dumpcycle parameter to decide how long it will refuse to 
> overwrite a tape. Thus, if you have a dumpcycle of 1 week and you use a 
> tape on monday, you can't reuse it until the next monday.

Close, but not quite.  Amanda also has a tapecycle parameter telling it
how many tapes are used per dumpcycle.  This is what determines which
tapes can be reused.  If you have dumpcycle = 1 week and run a tape on
Monday, then skip Tuesday-Friday, amanda will still refuse to overwrite
that tape the following Monday, even though a week has passed, unless
your tapecycle is set to only 1 tape.

> The danger of 
> leaving the tape in the drive is that sooner of later you'll find that the 
> part you need for an urgent restore, has been overwritten.

That is a concern with appending to a single tape, but the major issue is
that something outside of amanda's control (user unloading and reloading
the tape, another process, a SCSI reset...) could cause the tape to
be rewound.  This is undetectable on many tape drives and would result
in the loss of all the previous backups on the tape.  As this would be a
catastrophic failure, amanda is quite insistent in her refusal to append
to a tape.

> Judging from your message, maybe a simple script that uses dump or tar would 
> be more convenient for you. You could write a simple script that dumps 
> whatever you want to a non-rewinding tape and leave it there.

Agreed.  From what the OP has told us, I doubt that amanda is the right
tool for his needs.  I tend to agree with Paul that rsync would probably
be the best choice, although a custom script that checks for changes
and prepares a tarball for download if necessary would also work.
(But setting up rsync would be a lot easier, provided you can get ssh
access to the box...)