No matter the ETL tool used, there are some basic patterns to follow when transferring data between systems. There are many data tools and platforms, but the basic patterns remain the same. This focuses on SQL Server, but most of these methods work in any data platform. Even if you are using a virtualization layer, you likely need to prepare the data before exposing it to that engine, which means ETL and data transfers.
Warehouse is very loosely a data warehouse, but the same process applies to other systems. This includes virtualization layers, and to a smaller degree, bulk transfers