chunk archiving

hello everybody!! i've got the very common problem of archiving out of date data, let's say the production data older than 3 years. my plan was like this: grouping the data onto yearly changing dbspaces like ar1997, ar1998 ... each dbspace is designated to a distinct chunk, which i want to remove after 3 years. i'm free decide to put the data in tables with annual extentions, or fragment them by year(date). it's no problem for my database (7.12 UC3 on AIX) to handle the fact that the dbspace is unreachable, but when i try to to restore the dbspace: BAD PRIMARY CHUNK! :-( and my dbspace remains offline. the same problem has to occure to anybody wanting to bring a dbspace onto any removeable media. i'm astonished not finding more about that problem in the FAQs. thanks. peter