Sas Expander Connections - Adaptec RAID 2405 Installation And User Manual

Some backplanes support daisy-chain expansion to other backplanes. For example, you can
daisy-chain (connect one to the next) up to nine Adaptec 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
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.
SAS SATA
Disk Drives
SAS
SAS Card
SAS SATA
Disk Drives
Appendix A: Introduction to SAS
SAS Domain SAS Domain
Disk Drives
SATA
Disk Drives
SATA SAS
SAS Card
Fanout Expander
SAS Card
SAS SATA
Disk Drives
page 71), support
SATA
Disk Drives
SATA
SATA
Disk Drives
SAS
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