Existing approaches to delivering persistent block storage in OpenStack focus on integrating existing SAN/NAS hardware solutions, using Distributed File Systems (DFS), or using simple Direct Attached Storage (DAS) with Cinder. There is another alternative: scale-out block storage nodes with intelligent scheduling. This is the same approach that Amazon Web Services (AWS) uses for Elastic Block Storage (EBS) and it's worth taking a close look at the pros and cons. This presentation will explore the differences between SAN, NAS, DFS, DAS, and EBS. We will look at the implicit and explicit contracts that users and operators get from the different approaches and look at a variety of failure conditions. EBS may not be right for some clouds, but for many it's an important and viable alternative to the existing approaches.