We took a snapshot of our Cache-hit-ratio, which is applicable for our HTTP delivered traffic and came up with the following:

73,894 Hits
- 80% cache hit
- 14% cache miss
- 4% expired cache hit
- 2% cache miss due to client refresh

Then I simply used out the calculator on S3 and run some different scenarios….
http://calculator.s3.amazonaws.com/calc5.html

Notice when you choose some of the customer scenarios (1/2 way down the long calculator near the Calculate Now button)…that their own scenarios show up to $1/GB:

Customer Sample 1: 100 GBs on S3 = Cost $102/month or $1/GB
Customer Sample 4: 400 GBs on S3 = Cost $149/month or $0.3725/GB
Customer Sample 7: 400 GBs on S3 = Cost $72/month or $0.18/GB
This last scenario is most ideal cost-wise with about 12% outbound traffic so its about 40% less than what we’re doing now.

Bottom line is that our service with S3 has unpredictable cost, no 100% uptime SLA, and support that requires payment. Its the cheap solution but it can get expensive quickly depending on the nature of our traffic.

Since EdgeCast is stomping s3 performance wise, according ot our Gomexz testing, we are probably going to go with them.

Darby