Archiving help

[Birched]

We have an active board with about 3 million posts. Although I have seen this described as 'not that big' on the boards, we are nonetheless having issues with the size of the database, both in terms of some long database operations and also the time associated with backups and upgrades.

I am wondering if there is any accepted way to separate away (but still keep as viewable) older threads that vBulletin might label as 'archived' (i.e. users can read but not post) in such a way that they could be handled separately (and less frequently) for the purposes of backup and other maintenance.

Thanks for any thoughts,
B.