Sheepdog is a distributed storage system for KVM. It provides highly available block level storage volumes that can be attached to KVM virtual machines. Sheepdog supports advanced volume management features such as snapshot, cloning, and thin provisioning. The architecture of Sheepdog is fully symmetric; there is no central node such as a meta-data server. This design enables linear scalability in performance and capacity, no single point of failure, and easy administration. Sheepdog is distributed as an open-source software under the terms of the GPL. We will talk about the design, implementation, and experimental results of Sheepdog.