Seagate RealStor 5005 Series Hardware Installation page 40

NOTE: For clarity, the schematic diagrams show only relevant details such as IOM face plate outlines and expansion
ports. For detailed illustrations see
0A
0B
1A
1B
2A
2B
C
3A
3B
C
Add enclosures up to maximum (10)
9A
9B
C
Figure 29 Cabling connections between a 2U controller enclosure and 2U expansion enclosures
The diagram above (left) shows reverse cabling of a 5005/4005 Series dual-controller 2U enclosure and supported 2U
drive enclosures configured with dual expansion modules. Controller module 0A is connected to expansion module 1A,
with a chain of connections cascading down (blue). Controller module 0B is connected to the lower expansion module
(9B), of the last expansion enclosure, with connections moving in the opposite direction (green). Reverse cabling allows
any expansion enclosure to fail—or be removed—while maintaining access to other enclosures.
The diagram at right (above) shows the same storage components connected to use straight-through cabling. Using this
method, if an expansion enclosure fails, the enclosures that follow the failed enclosure in the chain are no longer
accessible until the failed enclosure is repaired or replaced.
The 2U drive enclosures shown in the above figure can either be of the same type or they can be a mixture of the J1212
and J1224 models. Given that supported drive enclosure models use 12Gb/s SAS link-rate and SAS 3.0 expanders, they
can be ordered in desired sequence within the system, following the controller enclosure. The middle SAS ports on
expansion modules are not used. See also
diagrams when cabling multiple expansion enclosures together with 5005/4005 Series controller enclosures.
40 Installation
"Enclosure rear panel" (page
Controller A
Controller B
A C
C A
A C
A
A C
A
A C
A
Reverse cabling
20).
Figure 12 (page 21) and the Important text beneath that figure. Refer to these
Controller A
Controller B
A
C A
A C
C A
A C
C
A
Add enclosures up to maximum (10)
A
C
C A
Straight-through cabling
0A
0B
C
1A
1B
2A
2B
3A
3B
9A
9B