236 IBM eX5 Implementation Guide6.5.2 Processor requirementsTo maximize performance, both nodes must have all four processors and all memory cardsinstalled and populated. However, the x3850 X5 does support 2-node configurations with onlytwo processors installed in each node.The following list shows the processor requirements to perform scaling: Functioning processors must exist in processor sockets 1 and 4 of both servers. The processor specification must match among all processors in both servers.6.5.3 Memory requirementsFor scaling to be permitted, you must install the memory in such a way so as to supportHemisphere Mode on the processors of both nodes. See Table 3-15 on page 81 to see whichmemory configurations enable Hemisphere Mode.To maximize performance, all four processors in both nodes must be in Hemisphere Mode. Ifneeded, the servers can be scaled with only processors 1 and 4 in Hemisphere Mode in bothnodes, but this type of configuration cannot support operating systems, such as VMware. Forother less sensitive operating environments, if the unlikely failure of a memory card takesprocessor 1 or 4 out of Hemisphere Mode, you can restore the scaled environment byswapping memory cards from processor 2 or 3.6.5.4 Cabling the servers togetherThe QPI cables that are used to cable the two x3850 X5s together are extremely short andstiff. To plug the cables in, you must start the cable insertion on both sides of the cable intothe correct receptors on both x3850 X5s at the same time.Use the following tips when plugging in the cables: QPI cables ship packaged with reusable plastic boots that protect the fragile outsideedges of the cable connectors, as shown in Figure 6-12. It is a good idea to keep a set ofthese plastic boots if you want to remove the QPI cables for the movement of equipmentfrom rack to rack or for servicing the unit.Figure 6-12 Reusable QPI cable connector protective boot
