Expert Oracle Exadata - Parent Directory

CHAPTER 15 COMPUTE NODE LAYOUTspine switch. The spine switch is included with all half rack and full rack configurations. Quarter rackconfigurations do not have a spine switch and cannot be linked with other Exadata racks. In a full rackconfiguration, the ports of a leaf switch are used as follows:• Eight links to the database servers• Fourteen links to the storage cells• Seven links to the redundant leaf switch• One link to the spine switch• Six ports openFigure 15-4 shows an Exadata full rack configuration that is not linked to any other Exadata rack. It’sinteresting that Oracle chose to connect the two leaf switches together using the seven spare cables.Perhaps it’s because these cables are preconfigured in the factory, and patching them into the leafswitches simply keeps them out of the way and makes it easier to reconfigure later. The leaf switchescertainly do not need to be linked together. The link between the leaf switches and the spine switchdoesn’t serve any purpose in this configuration, either. It is only used if two or more Exadata racks arelinked together.Spine SwitchLinks to 8 DatabaseServers7 Inter-switch linksLinks to 8 DatabaseServersLeaf Switch 1Leaf Switch 2Links to 14 Storage CellsLinks to 14 Storage CellsFigure 15-4. An Exadata full rack InfiniBand networkThe spine switch is just like the other two InfiniBand switches that service the cluster and storagenetwork. The diagram may lead you to wonder why Oracle would make every component in the rackredundant except the spine switch. The answer is that redundancy is provided by connecting each leafswitch to every spine switch in the configuration (from two to eight spine switches).To network two Exadata racks together, the seven inter-switch cables, seen in Figure 15-4, areredistributed so that four of them link the leaf switch with its internal spine switch, and four of them linkthe leaf switch to the spine switch in the adjacent rack. Figure 15-5 shows the network configuration fortwo Exadata racks networked together. When eight Exadata racks are linked together, the seven inter-508