How Do Sas Devices Communicate; What's A Phy - Adaptec SAS/SATA/SCSI RAID Controllers Installation And User Manual

How Do SAS Devices Communicate?

SAS devices communicate with each other through links. A link is a physical connection
between two phys.
As shown in the following figure, SAS devices contain ports (see
and each phy contains one transmitter and one receiver—one transceiver. A phy can belong to
one port only.
SAS Device
Narrow
Receiver
Phy
Port
Transmitter
SAS Device
Receiver
Phy
Transmitter
Wide
Port
Receiver
Phy
Transmitter
Receiver
Phy
Transmitter
Receiver
Phy
Transmitter
Wide
Port
Receiver
Phy
Transmitter
Receiver
Phy
Transmitter

What's a Phy?

Phys are part of the physical communication connection between SAS devices. Each phy
contains a transceiver that sends data back and forth between SAS devices.
When a connection is formed between two end devices, a link is established from a phy in one
port to a phy in the other port. As shown in the figure above, a wide port can support multiple
independent links simultaneously.
Phys are internal, within SAS connectors (see
SAS cables physically connect one or more phys on one SAS device to one or more phys on
another SAS device.
Appendix A: Introduction to Serial Attached SCSI
SAS Device
link
Narrow
Transmitter
Phy
Receiver
Port
Transmitter
Phy
Receiver
Wide
Port
Transmitter
Phy
Receiver
SAS Device
Transmitter
Phy
Receiver
Transmitter
Phy
Receiver
Wide
Port
Transmitter
Phy
Receiver
Transmitter
Phy
Receiver
page 65).
64
page 65), ports contain phys,