I have 3 MTs, all running 3.23, and try to back these up. Two of the MTs back up all right, but the third one, a RB532A, refuses to do that as it gobbles all disk and stops when the disk is full (after aprx 23 Mb). Then it gives an error messages saying that it cannot create backup errorcode 6.
This MT is bridged to one of the others via a cable running between the two of them and has two AR5413 interfacecards serving 2-4 users.
I can’t remember which version was it, but in one of earlier versions there was a bug where all kind of rubbish was saved in backup file.
Upgrade to v3.28 and it should be fine.