2.2.1 Two-system node drawers OP-bus connection
In the two system drawer configuration, two OP-buses interconnect the processors between the two drawers. Figure 2-12 shows all the connections between the SMP ports of the first system node drawer with the SMP ports of the second system node drawer that are accomplished by using the proper set of cables.
Figure 2-12 Two system node drawers SMP connection
The length of every cable is 775 mm (2.5 ft.) and its tape color is violet. As Figure 2-12 shows, 16 cables are needed for this configuration.
Chapter 2. Architecture and technical overview 71
2.2.2 SMP cable RAS attribute
Each SMP bus has 18 lanes and it is split between two separate cables, where each cable has nine lanes. An SMP spare lane is used on each SMP cable (eight lanes for data and one lane as spare). If one of the two SMP cables fail, all the traffic is routed to the one remaining cable, which reduces the bandwidth by half.
The Power E1080 supports concurrent repair of the external SMP cables; therefore, the entire server does not need to be shut down to replace an external SMP cable.
The concurrent repair process enables the system to restore the OP-bus to the full function without a system outage.