Today, Amazon EC2 went from beta to a released service and with it they have implemented a service level agreement (SLA). It's not the best SLA I've seen, but it's a start. The gist of it is: If, over a year the service drops below 99.95% available then you're entitled to a 10% refund of that year.
<p>Obviously there's a few problems with that.</p> <ol> <li>99.95% isn't the best uptime.  I would have liked to have seen at least 99.99%  But for many applications, it probably will be an acceptable amount of downtime.  Add the fact that you have the possibility of hosting in multiple availability zones, and you can mitigate the risk fairly effectively. </li> <li>You either have to be a customer for an entire year before you get any redress for 99.95%.  OR they have to have such terrible uptime that it becomes statisitcally impossible for them to hit 99.95% for that year. A per-month SLA would have been better. </li> <li>A 10% credit is pretty meager.  But at least it's for the entire period and not for the downtime amount.  This means if I spend $200 a month for a year, they hit 99.94% uptime, I get a $240 credit. But that's it.  If they're at 90% uptime I get the same credit. </li> </ol> <p>I think this SLA will help with convincing business folks that EC2 is a viable service, but probably not so much to actually help mitigate damages.</p> <p>Compared to the <a href="http://www.google.com/apps/intl/en/terms/sla.html">google apps SLA</a>, it's a lot better.  It'll be interesting to see how the Google App Engine SLA turns compares when they implement one. <br /> </p><p></p>