Disaster Recovery is a big topic. For the sake of this post we can limit it to 2:

High availability

If you are asking about load balancing, you probably want high availability. You can achieve HA by running your app on multiple instances so that in the event one fails, due to hardware or out of memory etc, requests would still be handled by another healthy instance until unhealthy ones are recovered. For this setup I highly advise to go for container model:  https://github.com/mendix/docker-mendix-buildpack (or mendix for private if you need it). You can try to do it with regular VM’s also but it will cause lots of headaches, but achievable.

Data recovery

We are all human, so we can sometimes make operational or development errors that causes the application change or delete data it should not have had done. In that event, you need data recovery. In Mendix this means you need to keep snapshots of your database and file store so that you can restore these when needed.