Backup Issue

Hello, OS = HPUX11 IDS = 9.21.FC4 The nightly backup (onbar -b -L 0) on one of our supported systems is taking in excess of 3 hours to complete. This is due to the user having archived data (arcdbs ) within the live instance. The customer has recently asked if there is any way to exclude the arcdbs dbspace from the nightly backup to improve backup and recovery times....I have replayed saying this is not a valid option(?) (I am pretty sure I am correct on this)....so the customer has requested a further solution. What would your solutions be to this problem.....I was thinking of having a separate database for the archived data within the live instance then back it up once a month etc... or maybe have a completely separate instance to accommodate the arcdbs. Any thoughts would be greatly appreciated... Cheers, Howard