Adaptec 44300 Installation And User Manual

Also see for 48300: Datasheet Installation and user guide

Contents

Adaptec 44300 Installation And User Manual Manual pdf 54 page image

Appendix A: Introduction to SAS ● 54As shown in the following figure, SAS devices contain ports which contain phys (see nextsection), and each phy contains one transmitter and one receiver—one transceiver. A phy canbelong to one port only.What’s a Phy?Phys are part of the physical communication connection between SAS devices. Each phycontains 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 oneport to a phy in the other port. As shown in the figure above, a wide port can support multipleindependent links simultaneously.Phys are internal, within SAS connectors (see page 55).SAS cables physically connect one or more phys on one SAS device to one or more phys onanother SAS device.What’s a SAS Port?Note: Because the physical link between SAS devices is from phy to phy, rather than portto port, a “port” is more of a virtual concept, different from what is normally considered aport on other types of RAID controllers and storage devices.A port is one or more phys. A narrow port contains one phy. A wide port typically contains fourphys.Each port has its own unique SAS address (see page 55), and all the phys in a port share thatsame SAS address.SAS card port options vary. A SAS card with four phys could be configured with one wide port,with two wide ports that comprise two phys, or with four narrow ports each containing onephy. (A wide port with four phys is referred to as a 4-wide or 4x port.)WidePortWidePortPhy ReceiverTransmitterPhy ReceiverTransmitterPhy ReceiverTransmitterPhy ReceiverTransmitterPhy ReceiverTransmitterPhy ReceiverTransmitterPhy ReceiverTransmitterNarrowPort PhyReceiverTransmitter NarrowPortSAS DeviceSAS DeviceSAS DevicePhyReceiverTransmitterPhyReceiverTransmitterPhyReceiverTransmitterPhyReceiverTransmitterPhyReceiverTransmitterPhyReceiverTransmitterWidePortWidePortSAS Devicelink