linodes on different machines in same datacenter

We don't offer a way to select which host machine your Linode is deployed on, but if you reach out to our Support team, we can help to verify that your replicated Linodes are not kept on the same host. It's important to know that while it's unlikely for your three Linodes to land on the same host, resizing or migrating a Linode will change its original host. With that in mind, something you may want to consider is using the Linode Kubernetes Engine to manage database replication across different Linodes. It will also be helpful to review our high availability guide, as there are some tips for failover and redundancy that might be useful to keep in mind.