TIM SAID :
I agree with what Dan said - it is difficult to give you advice without knowing your hosting requirements. If you can tell us a little more about what you are trying to do, we might be able to help.
What I can tell you is that since my original post back in early January, the configuration that I had settled on (an "m1.xlarge" configuration with 8 ECUs, 4vCPUs, 15Gb Memory, 4 x 420 Gb storage, and High network performance) has proven to be very successful. I have been amazed at the performance that we are getting, and we have had no downtime whatsoever. Many of my clients have even mentioned to me how much faster things are. In fact, things have been so successful that I just finished migrating all of my hosting clients to EC2, and I have pulled the plug on our dedicated Mac-based servers.
I am surprised at how enthusiastic I am about EC2. You see, in the past I have been strongly oppossed to using virtual servers in general, and especially for hosting FileMaker. However, I am glad that I explored EC2. My only concern at this point is the price, although I do believe that in this case you truly get what you pay for.
FMI has stated the recommended specs in terms of processing power and memory:
I think those tend to be on the low side but much depends obviously on the design of the solution and the nature of the user's interaction with it.
Basically we are talking about a single DB file or two the most but with possibly many users connecting via WD only.
One DB has about a dozen tables and about 30 layouts, of which around half a dozen will get most traffic. All layouts are optimised with all Theme edits saved. A few heavy processes are using PSoS and there are no calculation fields. Just a lot of related text and at most 4 portals on a layout.
The other DB has only 4 tables and just 6 layouts. Again optimised.
I hope this helps in the answers.
Regarding scalability, the hourly cost is quite expensive but the annual or tri-annual is not that bad. But can you scale to another contract that way? Say you get an annual contract for t2.medium and then decide to move t2.large after 4 months. Can you do these things?