This book offers a comprehensive resource on Solid-State Drives (SSD) as the field undergoes a radical evolution characterized by the incredible variety of SSD forms and their rapid diversification. It proposes a new classification system to help readers navigate the SSD landscape. For years, the evolution of SSDs was obscured by the unchanging abstractions of block devices and POSIX I/O, but it is apparent that these abstractions have become a problematic hinderance to performance and also fail to reduce software complexity. The book explores how such a state of affairs impacts the database community in at least two ways. First, it considers how using SSDs through legacy interfaces that hide internal mechanisms invariably results in erratic performance. While the blame often goes to the notoriously expensive garbage collection of SSDs, the authors argue that in truth, several other complex processes result in nonlinear effects on latency and bandwidth. The book describes these processes and how they are implemented in modern devices, knowledge that will help system designers better choose SSDs and shape database workloads to match their performance characteristics. Second, the book explores how the inadequacy of the traditional I/O abstractions opens up an entire research field focused on the co-design of database management systems and SSD. Such research aims at devising mechanisms and policies coupling the storage manager of database and SSD internals, e.g., placing an SSD FTL under the control of database, changing SSD sub-systems in response to the workload, or executing logic within an SSD on a database’s behalf. The book introduces these principles of DBMS/SSD co-design and argues that a more seamless integration of databases and storage solutions as well as the study of SSD variations adapted to database computations are central to the development of the next generation of database systems.
