Your volume experienced a failure due to multiple failures of the underlying hardware components and we were unable to recover it.
Although EBS volumes are designed for reliability, backed by multiple physical drives, we are still exposed to durability risks caused by concurrent hardware failures of multiple components, before our systems are able to restore the redundancy. We publish our durability expectations on the EBS detail page here (http://aws.amazon.com/
Amazon has refused to refund the charges on this account and continued to charge as if the lost data was still there!
We test services such as EC2 and keep an open mind to adopting them if the results of a one year trial are positive. But this illustrates why such trials are necessary and why we will not be using Amazon to host our customers in the foreseeable future. They lost all the data on the volume and while they claim that this happens with a yearly rate of 0.1% - 0.5%, ie once every 200 - 1000 years, it happened to us after just 8 months.
After over ten years of service, such a failure has never happened on our infrastructure.