Chapter 5. Rack planning 145These switches do not feature front (port side) to rear cooling air flow, so they arenot good candidates for racks that feature NeXtScale systems because of thenumber of cables that must be routed from the front to the rear of the rack.5.6.2 InfiniBand switchesThe InfiniBand switches, which are listed in Table 5-13, are available as part ofthe Intelligent Cluster offering. As with the Ethernet switches that require coolingfrom the ports to the back of the switch, the InfiniBand switches need the sameair flow path. However, on the InfiniBand switches, it is referred to as oppositeport side exhaust (oPSE). It is recommend that the System NetworkingRecessed 19-inch 4-Post Rail Kit is installed for cable bend radius reasons.Table 5-13 InfiniBand switch feature codes5.6.3 Fibre Channel switchesFor I/O intensive applications, 8 Gb and 16 Gb Fibre Channel networks, whichare compatible with 8 Gb and 4 Gb storage devices, are popular because of theirhigh I/Os per second (IOPS) capability and high reliability. In larger clusters orsystems with high I/O demands, there are several nodes that are connected toSAN storage, which then share storage via a parallel file system (such as IBM’sGPFS) to the rest of the servers. Table 5-14 on page 146 lists the current IBM16 Gb Fibre Channel switch offerings. These switches should be mounted facingthe rear of the rack because they all have rear to front (port side) cooling air flow.The fiber optic connections must pass from the adapters that are installed in thefront of the NeXtScale nodes to the ports at the rear of the rack.10 Gb top-of-rack switchesA1M6 Cisco 3750X-48T-L (48 port, Layer 2/3)A4HP Edge-Core ECS5610-52S 10 GbE SwitchFeature code DescriptionFeature code DescriptionA2EZ Mellanox SX6036 FDR10 InfiniBand Switch (oPSE)A2Y7 Mellanox SX6036 FDR14 InfiniBand Switch (oPSE)6676 Intel 12200 QDR IB Redundant Power Switch (oPSE)6925 Intel 12200 QDR InfiniBand Switch (oPSE)
