Dear Muhammad,
For the sizing of the database for SMP, I agree with Kevin Bates as the database will not grow so big.
But you need to notice the size of the log file, it is recommended that you can use the function like auto-purge for the log file.
Then I see lots of incident that reported by the customer with out of JAVA heap memory size, it is recommended that you can use the memory more than 8G and set the JAVA heap memory size more than 4G.
Hope this can help.
Best Regards,
Charlie