And even if you do keep your important stuff on EBS, make sure you take snapshots on a frequent basis. We have received this email a couple of times:

    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/ebs).


    Sincerely,
    EBS Support

Fortunately, we had recent snapshots and it was a matter of (manually) spinning up a new instance from those.

Edit: proper quotation