Mainframe storage has been the backbone of large organizations for several decades, providing a robust, reliable, and secure foundation for data management and processing. As the volume of data generated by businesses continues to grow exponentially, the importance of mainframe storage in managing and protecting critical information has only increased. This book aims to provide a comprehensive guide to understanding, implementing, and optimizing mainframe storage systems in the modern era. In the age of cloud computing, big data, and artificial intelligence, mainframe storage remains a crucial component of the IT infrastructure for many enterprises. Despite the rapid evolution of technology, mainframes continue to offer unparalleled performance, scalability, and security for mission-critical applications. As such, it is essential for IT professionals, data center managers, and decision-makers to have a deep understanding of mainframe storage technologies and best practices. This book serves as both an introduction for newcomers and a reference for experienced professionals, covering a wide range of topics related to mainframe storage. We will explore the history, architecture, and various types of storage devices used in mainframe systems. Additionally, we will delve into storage management techniques, performance optimization, security, and disaster recovery.