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

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Appendix G Introduction to Serial Attached SCSI 109
When connecting to a backplane, the Sun StorageTek RAID Manager GUI enables
you to manage your system disk drives, see the
Sun StorageTek RAID Manager
Software User’s Guide .
The number of end devices is limited to the number of slots available on the
backplane. For example, the Sun S50 enclosure, which contains an expander, is a
backplane connection that supports up to 12 SAS or SATA disk drives.
Some backplanes support daisy-chain expansion to other backplanes. For example,
you can daisy-chain (connect one to the next) up to nine Sun S50 enclosures to a
single SAS card in a host system.
SAS Expander Connections
A SAS expander device literally expands the number of end devices that you can
connect together. Expander devices, typically embedded into a system backplane (see
“Backplane Connections” on page 108 ), support large configurations of SAS end
devices, including SAS cards and SAS and SATA disk drives. With expander devices,
you can build large and complex storage topologies.
There are two types of SAS expanders: fanout expanders and edge expanders . Each
performs a different role in a storage system. (For more information about how SAS
expanders work, refer to the STA Web site at www.scsita.org.)
You can connect up to 128 SAS ports to an edge expander. (A single edge expander
can therefore support up to 128 SAS addresses.)
You can connect up to 128 edge expanders to a fanout expander.
You can use only one fanout expander in any single SAS domain (a topology of
SAS—and possibly SATA—end devices and expander devices). A single SAS domain
can therefore comprise up to 16,384 SAS ports (and therefore up to 16,384 SAS
addresses including the fanout expander).
The next figure illustrates (in very basic terms) a SAS domain and shows how SAS
cards, SAS and SATA disk drives, and expander devices can fit together in a large
data storage topology.