Is Excel Calculation Services Needed on a PowerPivot for SharePoint Application Server?

Scenario: A SharePoint 2010 scale-out farm with two application servers:

APP1 – Runs Excel Calculation Services (ECS)

APP2 – Runs PowerPivot for SharePoint (R2 or 2010)

Do you need to start ECS on APP2 in order for PowerPivot for SharePoint to work?

Answer: You don’t but if you don’t have the updated Analysis Services OLE DB Provider on APP01, you’ll get the dreaded “Failed to create new connection…” error when you browse the PowerPivot workbook. SharePoint ships with the SQL 2008 ADO MD, MSOLAP, etc. stack; not the R2 or later components. Therefore, you must upgrade the OLE DB provider (R2 or 2010 depending on the PowerPivot version) as explained in the How to: Install the Analysis Services OLE DB Provider on an Excel Services Computer topic in Books Online.

Thanks to Dave Wickert for clarifying this.