US Patent 9753880 Method and switch for transferring transactions between switch domains

The disclosure generally relates to a PCIe switch that includes a selectively transparent bridge that selectively allows transactions to traverse between multiple PCIe domains without the encumbrance of each root complex entity requiring knowledge of the selectively transparent bridge. The bridge that enables the transactions is invisible to the root complex entity in a host and drive switch domain of the PCIe switch. No address translation of the transactions is required because the drive switch domain address map is a subset of the host switch domain address map. The bridge allows for extremely low latency transactions between host systems and storage drives because the bridge allows the storage drive to read the Direct Memory Access (DMA) Scatter-Gather List (SGL) directly from host memory. The bridge also allows I/O data reads and writes from the storage drive directly to the host memory without store and forward within a RAID controller's memory.