Cabling Connections Between A 2U Controller Enclosure And 2U Expansion Enclosures - Lenovo ThinkSystem DS Series Hardware Installation And Maintenance Manual

0A
0B
1A
1B
2A
2B
C
3A
3B
C
Add enclosures up to maximum (10)
9A
9B
C
Figure 55 Cabling connections between a 2U controller enclosure and 2U expansion enclosures
The diagram above (left) shows reverse cabling of a DS Series dual-controller 2U enclosure and supported DS
EXP 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 DS
EXP 2U models. Given that supported 2U 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
beneath that figure. Refer to these diagrams when cabling multiple DS EXP expansion enclosures together with DS
Series controller enclosures.
DS Series does not support intermixing of DS EXP and D3284 expansion enclosures when configuring a storage
system. Representative examples showing supported configurations and configuration limits are provided above
68 Installation
Controller A
Controller B
A C
C A
A C
A
A C
A
A C
A
Reverse cabling
Controller A
Controller B
A
C
A
C
A
C
Add enclosures up to maximum (10)
A
C
Straight-through cabling
Figure 21 (page 29) and the IMPORTANT entry
0A
0B
C
1A
1B
A
C
2A
2B
A
C
3A
3B
A
C
9A
9B
A