Semantically-Smart Disk Systems

SEMANTICALLY-SMART DISK SYSTEMS Muthian Sivathanu Robust and efficient storage of data is a prerequisite of current and future computer systems. To keep pace with both rapid changes in technology as well as increasing demands from applications and users alike, storage systems must evolve in new and interesting ways. Unfortunately, storage systems today have a problem: the range of functionality they can provide is fundamentally limited, despite the presence of significant processing power within them. The main reason for this limitation is that storage systems communicate with the outside world through a narrow block-based interface today, and therefore lack higher-level “semantic” understanding about how they are being used. This thesis proposes a solution to this fundamental problem. It presents a new class of storage systems called “semantically-smart disk systems” (SDS’s); such disk systems are capable of providing entirely new classes of functionality by exploiting information about the system above (e.g., a file system or a database management system). An SDS does so by carefully monitoring the lowlevel stream of block reads and block writes that a storage system normally sees, and then inferring higher-level behaviors of the system above. Importantly, an SDS does so without any changes to the