SAS Expander Fast Context Switching for SATA Devices

The patent applies preliminary action by pre-establishing multiple connections between the initiator device and different SATA target devices before switching is needed. The expander maintains these connections in a held state with resources pre-allocated, so when a switch is requested via SAF frame, the connection is already prepared and can be activated immediately without the overhead of closing and re-opening connections.

The patent implements dynamics by enabling the expander to dynamically hold multiple connections in a suspended state simultaneously, rather than maintaining only one active connection at a time. The expander can quickly transition between held connections based on switching requests, allowing flexible and rapid connection changes without permanent establishment of all connections.

The patent applies universality by designing the expander to handle multiple connection states (active, held, suspended) through a unified control mechanism. The same expander logic that manages traditional single active connections is extended to manage multiple held connections using the existing SAS protocol framework, avoiding the need for completely separate complex control systems for each connection type.

The patent uses the SAF (Switch Address Frame) as an intermediary mechanism that simplifies the switching control process. Instead of requiring complex direct control logic between initiator and multiple SATA devices, the SAF frame serves as a standardized intermediary signal that the expander processes to trigger pre-established connection switches, reducing the complexity of control logic.