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SAS Expansion Enclosure Configuration
The SAS expansion port connects to the expansion enclosures. For Dual-Controller systems, each
expansion port connects a controller to a corresponding expansion enclosure controller making fault-
tolerant links to different SAS domains.
The following principles apply to Unified Storage System and expansion enclosure connections:
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Dual Controller Unified Storage System connects to Dual Controller expansion enclosures.
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Single Controller Unified Storage System connects to Single Controller expansion enclosures.
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A longer cable is available for making expansion links with a Dual-Controller configuration. A longer cable
is required if connections to expansion enclosures are made from two opposite directions. Routing
through two different connections can avoid loss of data links if one enclosure fails in between.
There is a rotary ID switch on every expansion enclosure
that is manually configured using a flat blade screwdriver.
Configuring enclosure IDs:
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The configurable IDs for expansion enclosures are from 1 to 15. Usually the numbering starts from the
one closest to the managing Unified Storage enclosure.
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Make sure a unique ID is configured on each expansion enclosure so that the SAS WWN addresses of
disk drives can be properly assigned. Unified Storage System firmware automatically manages these
addresses.
Configuration Rules
How to connect SAS interfaces across Unified Storage System and expansion enclosures:
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Fault-tolerant links in a Dual Controller combinations: Corresponding to SAS drives’
dual-ported
interface,
two physical links are available from each disk drive, routed across the backplane board, each through a
SAS expander, and then interfaced through a 4x wide external SAS port.
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With data paths through separate SAS domains, access to disk drives can be continued in the event of
a cable link or SAS expansion enclosure controller failure.
