[toomuchtodo]

us-east-1 data is replicated to another region on the west coast behind the scenes. Its supposed to fail over automatically.

http://shlomoswidler.com/2009/12/read-after-write-consistenc...

> Aha! I had forgotten about the way Amazon defines its S3 regions. US-Standard has servers on both the east and west coasts (remember, this is S3 not EC2) in the same logical “region”. The engineering challenges in providing read-after-write consistency in a smaller geographical area are greatly magnified when that area is expanded. The fundamental physical limitation is the speed of light, which takes at least 16 milliseconds to cross the US coast-to-coast (that’s in a vacuum – it takes at least four times as long over the internet due to the latency introduced by routers and switches along the way).