[Answered ]-Advice on Amazon Web Services Setup for Django Back end & iOS Front end

The answer largely depends on your tolerance for downtime vs your monthly budget for AWS. A few points:

• Never run anything important on a single instance. For your app tier, you should be using a minimum of two instances, each in separate AZ, with load distributed by an Elastic Load Balancer.

• For Postgres, set up two instances (also in separate AZ’s) and configure replication. I’d also highly recommend that you use provisioned IOPS EBS volumes and provisioned IOPS-optimized instances.

• Definately look into Elastic Beanstalk. This will greatly simplify setting an autoscaling app tier and make it a snap to deploy code to it. This will also make it easy to set up separate staging and production environments so you can Q&A your code before rolling it to users.

• Consider setting a VPC for increased security and more control over your network resources. There’s a bit of an initial learning curve, but it’s worth it, especially when you plan to set up DB replication.

• Set up SNS alerts via CloudWatch alarms so you get notified when things break.

• Scale out before you scale up. Meaning, use a greater number of smaller instances before you move up to larger instances. This minimizes the impact of a single instance failure in your autoscaling group. It also allows more granular autoscaling. Don’t use large instances until you’ve benchmarked your application and discovered that you need them.

• Once you know what size instances you actually need, purchase reserved instances to save yourself at least 40% over 12 months.

I go into more detail about some of these items (and provide a few other tips) on my blog.