This chapter will cover details concerning hardware that provides device connectivity and high availability to SATA system designs. SATA has limited connectivity and availability:

 Point-to-point serial links ○ Only allow for a single host to device connection

 Single-ported devices providing only one path to the device ○ If that port or path fails, then the device is no longer available to the host system

The Port multiplier and selector topic list includes the following:

 Port multipliers ○ Address connectivity ○ PM ports ○ Addressing ○ FIS modification, delivery, and Link layer protocol ○ Port and General Status and Control Registers (PSCRs and GSCRs) ○ PM commands, resets, error handling, and link power management

 Port selectors ○ Address availability ○ Active port selectors ○ BIST and resets ○ Power management, hot plug, OOB signaling, and speed negotiation

The Port Multiplier (PM) is a device that provides connectivity to the basic SATA architecture. Considering that SATA is a point-to-point interface, only one device can connect to a single host port.