1. Remove existing memory modules: Before adding new memory modules, the existing memory modules should be removed.
2. Add 16x 64GB DIMMs: The new DIMMs should be added, in this case is 16 DIMMs of 64GB each, which will expand the memory to the highest configuration available.
3. Shutdown the Database Server if running: The Database Server should be shutdown before adding new memory modules in order to prevent any possible data loss or corruption.
The steps required to expand an Exadata X9M-2 Database Server with the lowest memory configuration available to the highest memory configuration are as follows:
Shutdown the Database Server if running.
Remove existing memory modules.
Add 16x 64GB DIMMs.
For reference, the Oracle Exadata Database Machine X9M Implementation Essentials Official Text Book states that "the lowest memory configuration for the Exadata X9M-2 Database Servers is 384GB and the highest is 768GB [1]. The memory upgrade is done in increments of 64GB using 16x 64GB DIMMs".