Book excerpt: Organizations today depend heavily on their data. Even short periods of data outages can be expensive and result in loss of productivity, as well as financial consequences, while permanent data loss can be catastrophic. Therefore, reliability and means to efficiently store and access such data is an important component of most large organizations' IT infrastructure. Much of this data is still stored in the most versatile format, the 'flat file'. This eBook provides both an academic and historic perspective on the development of distributed file systems and details some of the core algorithms, such as quorum protocols that are used in distributed storage systems. This book can be used as a short, stand-alone introduction to the field or as a resource for an academic course in the topic.