We did a test of an EC2 data centre setup vs. our existing physical data centre setup and the largest issue - that is, if you ignore the 3x cost - is the network latency and general quality of the local network in the availability zones.
No amount of optimization could eliminate the 100-150ms penalty imposed by the EC2 network vs. our dedicated hardware. The local network was congested and "noisy" in the sense that ping times were highly variable and had high packet loss, and the number of hops to the internet at large were high, and the baseline latency to the world was also high.
As for instance lifespan, we had numerous instances just "disappear" and then needed to be recreated. We were running a hundred or so for our test so YMMV.
No amount of optimization could eliminate the 100-150ms penalty imposed by the EC2 network vs. our dedicated hardware. The local network was congested and "noisy" in the sense that ping times were highly variable and had high packet loss, and the number of hops to the internet at large were high, and the baseline latency to the world was also high.
As for instance lifespan, we had numerous instances just "disappear" and then needed to be recreated. We were running a hundred or so for our test so YMMV.