8 years of dataA fixed time frame or rolling window? In the later case you need to consider one partition per year and a rolling window approach to add new years.
1.five)All those 5 tables has at least a date or datetime field?
basically make new databases right?I wanted to suggest only a single database for archiving. You just need to be sure about which old data to be move into archive (data that you're almost sure it won't be accessed anymore).
database_2003
database_2004 etc? (and delete 2003/2004 data)
Instead of partitioning you can also move the old data to an archived database. This will be good if you know that older data won't be needed anymore but you still have it archived just in case of future need.