The ONEZONE_IA offers the best alternative for low cost and real-time access but at the cost of a higher probability to lose your data. This storage layer will only replicate objects at the AZ level with 119s but it is not resilient to the complete loss of the AZ.

The RSS (REDUCED_REDUNDANCY) layer provides low cost and low replication ratio, RRS objects have an average annual expected loss of 0.01% of objects. If an RRS object is lost, when requests are made to that object, S3 returns a 405 error.

Let’s assume you are storing 800 MB files in size and you have 1 PB of data. With RSS you can expect to lose .01% of your files every year.

.0001 x 1.2 Billion = 12 Million files lost per year