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Chapter 2: Hardware installation
2.3.5 Expansion connections
When expanding your system, you can add expansion systems and connect between devices via the
SAS ports or the added SAS 12 G host board.
A SAS host link cable is bundled per expansion package. If you need to purchase other cables, or if you
need other cables of different lengths, contact your vendor.
Before configuring the expansions, you must take note of the following important points:
•
For a cleaner and clutter-free rack system, have a carefully planned routing paths when connecting
between systems.
•
All SAS cables are sensitive and must be handled with care. DO NOT bend or twist the cables
when connecting the systems installed to the rack.
Configuring the SAS expansion
The SAS expansion port of the GSa system connects to the expansion systems. For dual-controller
systems, each expansion port connects to a controller of another expansion system, making a fault-
tolerant linkage to different SAS domains.
The following principles apply to main storage and expansion system connections:
•
Dual-controller main storage connects to a single-controller expansion system
•
A longer cable is available in making expansion links with a dual-controller configuration. If you
need to connect expansion systems from two opposite directions, you may need a longer cable.
Routing between two different connections can avoid loss of data links if one expansion fails to
operate.
Setting the expansion IDs
Each expansion system must have a unique ID and you can configure the ID via the rotary ID switch. To
set the expansion IDs, use a small flat-blade screwdriver.
You must take note of the following when setting the IDs on the expansion system:
•
Set the IDs from 1 to 15. The order starts from the expansion enclosure that is closest to the
managing GSa enclosure.
•
Ensure to set a unique ID on each expansion enclosure so
that the SAS WWN addresses of the disk drives are properly
assigned. The storage system firmware automatically
manages these addresses.
