30 IBM System Storage N series Hardware Guide3.2.2 IBM N62x0 MetroCluster and gateway modelsThis section describes the MetroCluster feature.Supported MetroCluster N62x0 configurationThe following MetroCluster two-chassis configurations are supported: Each chassis single-enclosure stand-alone:• IBM N6220 controller with blank. The N6220-C25 with MetroCluster ships thesecond chassis, but does not include the VI card.• IBM N6250 controller with IOXM Two chassis with single-enclosure HA (twin): Supported on IBM N6250 model Fabric MetroCluster requires EXN4000 disk shelves or SAS shelves with SAS FibreBridge(EXN3000 and EXN3500)Gateway configuration is supported on both models.FCVI card and port clarificationsIn many stretch MetroCluster configurations, the cluster interconnect on the NVRAM cards ineach controller is used to provide the path for cluster interconnect traffic. The N60xx andN62xx series offer a new architecture that incorporates a dual-controller design with thecluster interconnect on the backplane.The N62x0 ports c0a and c0b are the ports that you must connect to establish controllercommunication. Use these ports to enable NVRAM mirroring after you set up a dual-chassisHA configuration (that is, N62x0 with IOXM). These ports cannot run standard Ethernet or theCluster-Mode cluster network.“Stretching” the HA-pair (also called the SFO pair) by using the c0x ports is qualified withoptical SFPs up to a distance of 30 m. Beyond that distance, you need the FC-VI adapter.When the FC-VI card is present, the c0x ports are disabled.Although they have different part numbers, the same model of FC card is used forMetroCluster or SnapMirror over FC. The PCI slot that the card is installed to causes the cardto identify as either model.Tip: Always use an FCVI card in any N62xx MetroCluster, regardless if it is a stretched orfabric-attached MetroCluster.
