Each SPARC SuperCluster T4-4 contains three Sun Datacenter InfiniBand Switch 36 switches, in either the full rack or half rack version, two of which are leaf switches (the third is used as a spine switch to connect two racks together). The two leaf switches are connected to each other to provide redundancy should one of the two leaf switches fail. In addition, each SPARC T4-4 server, Exadata Storage Server, and Sun ZFS Storage 7320 storage controller has connections to both leaf switches to provide redundancy in the InfiniBand connections should one of the two leaf switches fail. For more information, see Understanding the Physical Connections.