Ok, I think I've tracked down part of the problem, it appears the user set the Primary Data Source as the Oracle Connection.
Apparently SSAS will perform a remote query from the Primary Data Source to the Secondary using OPENROWSET to get the Secondary Data Source data.
'Add a Secondary Data Source' section in the link here ... https://technet.microsoft.com/en-us/library/ms174600(v=sql.110).aspx
This explains why when Processing the cube it was returning an Oracle Error when trying to query the SQL data.
The Primary data source has been changed to the SQL Server connection and now we're getting a different but equally frustrating error. :hehe:
Cheers
Edit: New Errors
Internal error: The operation terminated unsuccessfully
Errors in the high-level relational engine: The 'OracleDataSource' secondary data source is not a relational data source, or does not use an OLE DB provider.
Errors in the OLAP storage engine: An error occurred while the dimension, with the ID of 'DimBlah', Name of 'DimBlah' was being processed.
Both data sources are currently setup using .Net Providers, from the error above it sounds like they can't be used and we need to revert to using OLE DB. We don't currently have OLE DB Drivers for Oracle setup on the server so we're currently battling with getting that to work, then attempting to Process the cube once that is working.
Can anyone confirm that using OLE DB Providers is required for this?