Enhanced memory savings in routing memory structures of serial attached SCSI expanders

摘要

Methods and structure are provided for representing ports of a Serial Attached SCSI (SAS) expander circuit within routing memory. The SAS expander includes a plurality of PHYs and a routing memory. The routing memory includes entries that each indicate a set of PHYs available for initiating a connection with a SAS address, and also includes an entry that represents a SAS port with a start tag indicating a first PHY of the port and a length tag indicating a number of PHYs in the port. The SAS expander also includes a Content Addressable Memory (CAM) including entries that each associate a SAS address with an entry in the routing memory. Further, the SAS expander includes a controller that receives a request for a SAS address, uses the CAM to determine a corresponding routing memory entry for the requested SAS address, and selects the port indicated by the corresponding routing memory entry.