On Thu, 2008-11-13 at 16:12 -0500, Dustin J. Mitchell wrote:
> On Thu, Nov 13, 2008 at 3:42 PM, Krahn, Anderson <AKrahn AT gs1us DOT org> 
> wrote:
> > Is it possible for Amanda to use the same tape on multiple days until it
> > gets filled before using the next tape in the tape list?
> 
> Not directly.  The Device API supports appending to tape, but we
> haven't put together the configuration and mechanics to utilize that.
> 
> What most folks do is collect dumps on holding disk until they have a
> tape's worth.  The parameters taperflush, flush_threshold_dumped, and
> flush_threshold_scheduled are relevant.
> 
> Could someone who's using this technique add a How-To to the wiki?

I'm not currently using this technique but the below should work.  If no
one actually doing this beats me to it, I'll eventually put it on the
wiki.

The basic concept is to *not* make a tape available to Amanda.  In
absence of a tape, Amanda will write to holding disk (which needs to be
at least the size and hopefully more than the size of your tapes).  When
the amount of data on your holding disk is over the capacity of a tape
(assuming runtapes=1), run "amflush <config>".  This will flush as much
data on the holding disk to tape as possible and thus fill the tape.

In addition to the parameters Dustin mentions above, be aware that, by
default, Amanda will not write full backups to holding disk.  This
behavior can be changed with the 'reserve' parameter in amanda.conf.
This is set to 100 by default which says, in essence, to reserve 100% of
your holding disk for incremental backups only.

Thus, you can either load a tape whenever a full backup is due (maybe
not good if this is occurring weekly) or you can lower your reserve
parameter to allow for the size of however many full backups you may
want to write to holding disk before amflush'ing.

Paul

> 
> Dustin
>