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Configuring the SAS Expansion
The SAS expansion port of the PS 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
•
Singe 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 PS
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.
Configuration Rules
To connect the SAS interfaces across storage and expansion systems, you must take note of
the following:
•
Fault-tolerant links in a dual controller combination
Corresponding to the dual-port interfaces of the SAS drives, two physical links are
available per disk drive, routed across the backplane board, then to a SAS expander,
and interfaced via a 4x wide external SAS port.
•
With data paths via separate SAS domains
Access to disk drives can be continued in the event of a failure from a cable link or SAS
expansion controller.
