Toralf Lund wrote:

Ah, I see. So it won't actually multiply tape size by runtapes when trying to figure out how much it can write... I'm not sure the functionaltiy is of much use to me then, but perhaps I could cheat and pretend the tapes are "runtapes" times larger than they really are?

Maybe I missed something in this discussion, but Amanda does indeed
multiply the size by runtapes to measure the total capacity.
There is only the restriction that one single DLE still has to fit
on one tape.

I think it will buy me the ability to write, say, 4 tapes in 2 runs (2 in each run.) I can think of no other way to do that (given the information that amanda will schedule only one tape's worth of data even if I set runtapes to 2 or more.) I'm not saying that this is necessarily something I want to do, though.

That's exactly what it will buy you, yes indeed.
But no, it's not true that amanda will schedule only one tape's worth
of data when you set runtapes to 2.
Amanda actually schedules just as much to spread all dumps evenly over
the dumpcycle.  If you dumpcyccle is too large, maybe she won't reach
the capacity of one tape, even if you specified runtapes > 1.

If she hits a capacity limit (one tape or runtapes times one tape) she
will complain loud, but will to put as much as possible on the
limited capacity.

Another option I've been thinking about (again, if I decide I want to write several tapes in one go) is simply to start another amdump once the first is finished. I'm not sure if that's a idea either, though, since amanda seems to be geared towards one run a day, and it will probably increase overall backup time because dumps can't be parallelised between the two runs.

And you get a lot of incrementals / fulls done twice.

--
Paul @ Home