The RTM-5108 is a single slot (6HP) ATCA rear transition module of Advantech ATCA CPU blades. An Avago SAS3008 controller provides two SAS/SATA ports to two 2.5" Direct Attached Storage drives installed in the RTM-5108 storage trays and two miniSAS HD ports. One miniSAS HD port can be connected to external SAS devices (up to 4 devices). The other miniSAS HD port is used in a failover configuration, so two sets of compute blades and two RTM-5108 modules can be connected in a crossover mode to provide fail safe storage if used in conjunction with SAS disks supporting dual host ports. All internal and external SAS ports support 12Gbps lane speed. For rear LAN access, an Mellanox ConnectX-4 LX on the RTM-5108 provides two SFP28 ports on the RTM panel for 25GbE connections.