Experiments with Running WordpressMU on EC2 « Hefta-Gaub Development Blog

So the big issue with Ec2, and arguable grid computing vs dedicated servers is that you’re server instances don’t have a physical hard drive associated with them. Sure, they have disk space when they’re running, but as soon as they shut down that disk image is gone FOREVER… Obviously, if you plan to run a database on one of these machines, you have to think about this carefully.

It’s not like if you accidentally reboot your dedicated server at least you know your DB probably shut down safely, and will probably wake up working just fine. That disk is dedicated to you. But not so with EC2… that disk doesn’t exist anywhere. So you need to really think about how to make that disk image persistent.