Distributed-state-information-based distributed computing systems and methods and protocols for managing distributed state information

摘要

Various embodiments of the present invention are directed to distributed data-storage systems that provide non-distributed-data-storage-device-like interfaces to host computers that access the distributed data-storage systems. Distributed data-storage systems generally rely on state information used for execution of commands, received from host computers, by component data-storage systems. Command-executing component data-storage systems may access and modify state information shared among many or all of the component data-storage systems. Embodiment methods of the present invention provide methods for partitioning state information within a distributed data-storage system as well as communications protocols and methods for managing shared state information among the component data-storage systems within a distributed data-storage system. In certain embodiments of the present invention, state information is partitioned into one or more of: (1) local state information that is managed, accessed, and modified separately by each component data storage system; (2) shared state information that is locally cached on component data storage systems for immediate read access, that is periodically refreshed, but that is kept globally consistent among component data storage systems by distributing state-modifying operations; and (3) continuously consistent, shared state information.