SAP customers use copies of their production systems for various purposes: Upgrades should first be performed in a test system copied, perhaps, from production. New software development should be tested in a QA system copied from production before being moved to production itself. In these scenarios and more, being able to create a system copy is very useful indeed.
As of SAP NetWeaver 2004s you can copy ABAP systems, ABAP and Java systems, and Java systems in one run using either database-specific methods or database-independent methods. These guides explain how: