Amazon EC2 & S3
Thought I would shed a little more light on the Amazon AWS structure as a follow up from the brief discussion Tuesday night.
Amazon offers a ton of different services, and I don't understand all of them. A lot of the documentation could be wrote a lot clearer as well.
EC2 (Elastic Compute Cloud) is where the general hosting is done. It really isn't so much distributed, but more dynamic in its ability to scale on the fly. What you might think of as a single host, they refer to as instances. Instances are loaded with images (AMIs) You can roll your own, or use one of thousands that have been contributed by the community. There is little, to no documentation on the contributed images, so be cautious. However, there are official Ubuntu images available, and their numbers can be found at : http://cloud.ubuntu.com/ami/
Instances are priced 3 different ways. Standard, Reserved and Spot.
Standard is the most flexible, and the most expensive. The instance can be turned on and off at will, you will be billed as long as it is on. Usage doesn't mater. It can be turned off at any time, and billing will stop. You only pay for when it is on. Micro instances have 613mb of memory and start at 2 cents an hour. Capabilities and prices scale up to $2 an hour. A micro running 24/7 would cost about $175 a year.
Reserved Instances require you to pay a contract fee up front, and then you receive a discounted rate for the term of the contract. For example a one time fee of $54 will lock you in for $.007 per hour, for a year. You only pay the $.007 per hour when the Instance is on. A micro running 24/7 would cost about $115 for a year. A micro is capable of running a low volume Drupal site with no problems.
Spot instances essentially allow you to bid on unused capacity. You say what your max price per hour is, and how long you want it to be active. As long as the price is below your max, it runs. If the price goes above your max the instance shuts off till things cool down, or terminate base on your request. Typically the price on a micro is $.007 an hour, but the last 2 months have shown quite a few times where is has spiked up to about $.08 an hour. Prices change every 5 minutes! At $.007 an hour, 24/7 would be $61 a year. EDIT: An important difference is that Spot instances can not be shut off manually. Their life is dictated by the spot price, and the time you request them for.
The Standard and Reserved pricing is Ok, but not outstanding for a year, when there are some very good $15-$20 a month VPS options out there. However, they usually bill by the month, not the hour.
All EC2 instances are subject to transfer and request fees, but they are generally very low.
Then there is also S3, which is file storage. Kind of like a CDN, but not distributed by default. You can pick the datacenter though. This is ideal if you have large videos or other documents you want to host off site. Pricing starts at $.14 per GB and scales down after the first TB. There are also transfer and request fees, but they are very low.
I have a project that has some videos hosted on S3, and my AEgir Dev server backs up my live sites and the whole Dev server to S3 nightly. Currently the Dev server has 7 GB being stored, and my current bill is $1.05 a month.
Amazon offers a Free Tier, which is 750 hours of EC2 time, and 10 GB storage per month for 1 yr. They also offer 5 GB of S3 storage for 1 year. I am not sold on using them as my production host, but they have been a real handy tool for experimenting and short term needs.