30  IBM System Storage N series Hardware Guide
3.2.2  IBM N62x0 MetroCluster and gateway models 
This section describes the MetroCluster feature. 
Supported MetroCluster N62x0 configuration
The following MetroCluster two-chassis configurations are supported:
ň° Each chassis single-enclosure stand-alone:
⢠IBM N6220 controller with blank. The N6220-C25 with MetroCluster ships the 
second chassis, but does not include the VI card.
⢠IBM N6250 controller with IOXM
ň° Two chassis with single-enclosure HA (twin): Supported on IBM N6250 model
ň° 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 clarifications
In many stretch MetroCluster configurations, the cluster interconnect on the NVRAM cards in 
each controller is used to provide the path for cluster interconnect traffic. The N60xx and 
N62xx series offer a new architecture that incorporates a dual-controller design with the 
cluster interconnect on the backplane. 
The N62x0 ports c0a and c0b are
 the ports that you must connect to establish controller 
communication. Use these ports to enable NVRAM mirroring after you set up a dual-chassis 
HA configuration (that is, N62x0 with IOXM). These ports cannot run standard Ethernet or the 
Cluster-Mode cluster network.
âStretchingâ the HA-pair (also called the SFO pair) by using the c0x ports is qualified with 
optical 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 for 
MetroCluster or SnapMirror over FC. The PCI slot that the card is installed to causes the card 
to identify as either model.
Tip: Always use an FCVI card in any N62xx MetroCluster, regardless if it is a stretched or 
fabric-attached MetroCluster.