Number of CPUs and I/O subsystem details aid in determining the optimal number of export processes.
Source database sizes and sizes of the largest tables impact the duration of the migration.
During the first test migration, allocate 10%-15% of the uncompressed source database size as free space in the export file system.
Determine the approach for handling external files such as spool files, archives, logs, transport files, and interfaces that need to be copied to the target system.
If the source and target systems are located in different locations, decide on the available media or methods for transporting the dump files.
A migration test run is essential when for the production system
So as in any project we do the following and it will be talked in detail in later blogs , Final Migration Planning :
Create a cut-over plan
Perform the migration
Perform the follow-up tasks
Check the system
Run a backup
Start production work