Oracle SG-XPCIESAS-R-INT-Z, Installation Manual

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106 Sun StorageTek SAS RAID HBA Installation Guide • March 2010
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 “About SAS Connectors” on page 107 ).
SAS cables physically connect one or more phys on one SAS device to one or more
phys on another SAS device.
About SAS Ports
Note –
Because the physical link between SAS devices is from phy to phy, rather
than port to port, a “port” is more of a virtual concept, different from what is
normally considered a port on other types of RAID HBAs and storage devices.
A port is one or more phys. A narrow port contains one phy. A wide port typically
contains four phys.
Each port has its own unique SAS address (see “About Identifying Disk Drives in
SAS” on page 107 ), and all the phys in a port share that same 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 one phy. (A wide port with four phys is referred to as a
4-wide or 4x
port.)
About SAS Addresses
Each SAS port is identified with a unique SAS address, which is shared by all phys
on that port.
For example, a SAS disk drive might have two narrow ports. Each port has one
unique SAS address. The single phy in each port uses its port’s SAS address.
In another example, a SAS device might have one 4-wide port. That port has one SAS
address, which is shared by all four phys in the port.
Unlike SCSI devices and SCSI IDs, SAS devices self-configure their SAS addresses.
User intervention is not required to set SAS addresses, and SAS addresses cannot be
modified.