MySql server doesn't seem to be scale up correctly when scaling up my AWS instance. Its almost like MySql is cacheing the instance sizes.
This happens after a scale down the AWS instance and then when we scale back up the the AWS instance, the MySQL server seems to remain in the smaller state even though the AWS instance has doubled in RAM and CPU
Any suggestions?
MySQL doesn't adjust its settings according to the resources available on the server. For example, by default, it allocates a mere 128 MB for its InnoDB pool. It is expected that you read MySQL documentation and adjust settings according to your needs.
Alternatively, instead of running MySQL on EC2 you can run a managed AWS RDS MySQL instance, they have some settings already adjusted to the instance size.