Spool Cascading is a &Highwinds; innovation that allows a provider to use Tornado Back End in such a way as to store older articles on one server or set of servers and newer articles on one server or a set of servers without the need for duplication between the two sets. Before Spool Cascading, long retention servers needed to carry the most recent X days along with any short retention servers as well as all the articles older than X days. Now, a long retention server need only carry articles older than X days and the Tornado system will aggregate all the articles for the client to see.