I have a setup to backup lots of clients over slow links.
I want to have each client (or group of clients) backed up to dedicated client pools, so client1 will go to pool client1, and so on.
That way I have better control of the space used, if a client goes away I can simply delete the tapes (or files) an get the space back immediately.
Also it gives me better control on the retention on a per client basis.

The problem is that when I try to backup multiple clients at the same time, the storage process has to wait for each job to finish before it can move to the next because it needs to change the tape (different client --> different pool). Some clients may take many hours to finish, forcing everybody else to wait.

I enabled spooling, but it seems like Bacula requires to mount a tape from the client pool on a drive before the client spooling can begin.
Can this be avoided?

A possible solution would be to do all backups on a special pool and after they are done migrate later each client job to each client pool.
But I cannot find a way to modify  the "Next Pool" dynamically. It is a fixed setting on the Pool definition.

Does anybody have suggestions on how to accomplish this?