I have an EC2 instance on which I want to install Postgresql using Docker. Is it advisable to have two EBS connected, one root and one for data? Or could just a single one be enough? And for what reason?
In both cases, take periodic EBS snapshots.
It is advised to have the Postgresql data on a specific storage.
That way it simplifies the upgrade for instance, you change just the AMI and start a new EC2.
You should consider running your DB with RDS.