Dot Hill Systems 4524 - Reverse-Cabling between a Dual-Controller 4 U Enclosure and Three 2 U Drive Enclosures; Straight-Through Cabling between a Dual-Controller 4 U Enclosure and Three 2 U Drive Enclosure

48 Installing the enclosures
Figure 44 Reverse-cabling between a dual-controller 4U enclosure and three 2U drive enclosures
Figure 44 shows reverse cabling of a 4004 Series dual-controller 4U enclosure and 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 (3B), 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.
Figure 45 Straight-through cabling between a dual-controller 4U enclosure and three 2U drive enclosure
Figure 45 on page 48 shows the same storage components used in Figure 44, but they are connected
using 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.
Controller
enclosure
0
Drive
enclosure
In Out
Out
0B
0A
1A
1B
Controller A
Controller B
1
In
2A
2B
3A
3B
Drive
enclosure
2
Drive
enclosure
3
In Out
In Out
In Out
In Out
Controller
enclosure
0
Drive
enclosure
In Out
Out
0B
0A
1A
1B
Controller A
Controller B
1
In
2A
2B
3A
3B
Drive
enclosure
2
Drive
enclosure
3
In
Out
In Out
In Out
In Out