For instance, a machine can just “disappear”. You can set things up to automatically start a new instance to replace it, but if you just committed a transaction it’s likely to be lost: MySQL replication is asynchronous, EBS which is slower if you commit your transactions on it, or EBS snapshots which are only periodic (you’d have to add foo on the application end). This adds complexity, and thus the question arises whether EC2 is the best solution for systems where this is a concern.

When pondering this, there are two important factors to consider: a database server needs cores, RAM and reasonably low-latency disk access, and application servers should be near their database server. This means you shouldn’t split app and db servers to different hosting/cloud providers.

We’d like to hear your thoughts on EC2 in this context, as well as options for other hosting providers – and their quirks. Thanks!