On 05/14/2009 09:58 PM, Dustin J. Mitchell wrote:

On Thu, May 14, 2009 at 12:35 PM, Jeffrey D Anderson <JDAnderson AT lbl DOT 
gov> wrote:

I don't know if there is any real solution to that problem, though.  amanda
tries to balance the load evenly among the runs in each dumpcycle.  But
sometimes I'd rather she tried to keep me on a single tape, and then write
two tapes some night, rather than writing 1 1/4 tapes each night.  That would
save a lot of wear and tear on backup media.

Perhaps the solution is not in changing the planner behavior, but in taper
options.  It would be acceptible to me if amanda wrote most of the holding
disk files to tape, but elected to save some for the next night if it meant
better allocation of media.

There's room both for new planner algorithms and for interaction
between the planner and the taper.  At the moment, the planner
pretends it has a single tape of length (tapetype:$tapetype:length *
runtapes).

All of this is pretty far off in the future, sadly.  I can only code so fast :)

There is already "maxdumpsize":  the maximum amount that planner will schedule
for a run.  It defaults to numberoftapes times tapesize, but sometimes I prefer
to set it a little lower, because of the lost space a the end of each tape.

And there is also the "taperflush" parameter since 2.6.  Set it to some
percentage of one tapesize to avoid writing the last pieces of a run to a
new tape, when that amount to write is not large enough to fill a decent
proportion of the tape.

I believe with these parameters, you can achieve the desired result.
Or did I miss something?

--
Paul