Serial Attached SCSI - 4 is the next generation of Serial Attached SCSI, following SAS-3, SAS-2.1, SAS-2, SAS-1.1, and SAS. The following items should be considered for inclusion in Serial Attached SCSI - 4: 1) at least double the SAS-3 data rate; 2) maintain 6 Gbps and 12 Gbps SAS compatibility; 3) incorporate more efficient signal encoding; and 4) other capabilities that may fit within the scope of this project.