I am designing an Analysis Services system, the end goal of which is to throw up some pre-defined reports to end users. The SSAS side of things will be required to pull data in from several different databases on several different servers. The data will be updated daily, so possibly a scheduled ETL job will have to run every night to update with latest updates / inserts / deletions. We're not talking massive here, but several million rows being pulled from each system, and eventually there could be up to 20 odd different databases involved.
How am I best designing this? Should I create a Data Mart / Warehouse into which I should pull all the data and then design the SSAS project around this?