Heterogenous migration
Whenever there is a change to the operating system, DBMS software, or the hardware platform, the migration becomes heterogeneous. Rather than some form of relatively simple copy process, all data residing in the source database must be exported to flat files in the source environment, copied to the target environment, and then imported into the target database. This Export/Import method is more complex than backup/restore, but it offers additional capabilities, and as the basic migration tools are supplied and fully supported by SAP, this is the recommended option if you plan a platform change.
More recently, SAP has enhanced the basic Export/Import solution with a relatively new option to migrate systems to the cloud with the Database Migration Option with System Copy. It offers the same capabilities as the Classical Migration, but in addition you can perform a system upgrade or Unicode conversion in a single step.
Because the export files are much smaller...