Storage Subsystem Backend Network Topology for SSD HDD Coexistence

The patent segments the backend network into separate domains: SSD domains and HDD domains. Each domain is managed by dedicated expanders that do not interconnect, preventing performance interference. This segmentation allows SSDs to achieve high-speed access while still supporting a large total number of drives across multiple domains.

The patent introduces topology control mechanisms as intermediaries that manage and regulate network connections. The controller monitors and enforces topology rules to ensure SSD expanders are not connected in cascade, thereby mediating between the need for high SSD performance and the desire to connect many drives.

The patent segments the control architecture by creating separate control paths for SSDs and HDDs. SSDs are managed through dedicated expanders with simplified protocols, isolating them from the complex processor-intensive control mechanisms required for HDDs. This reduces the processing burden on the controller.

The patent changes the operational parameters of the backend network when SSDs are detected. Topology rules are dynamically applied to restrict cascade connections for SSD expanders, and communication protocols are optimized for SSD performance characteristics, thereby improving storage performance while managing controller complexity.

The patent physically segments the expander connection topology into separate SSD and HDD domains. SSD expanders are prohibited from cascade connections, ensuring dedicated high-speed paths. HDD expanders can use cascade connections without affecting SSD performance, as the two domains are isolated from each other.

The patent implements topology monitoring and control mechanisms that provide feedback about the current network configuration. When SSDs are detected, the system automatically enforces topology rules that prevent harmful cascade connections, thereby eliminating communication interference while maintaining necessary connectivity.