Figure 3-15 shows the suggested designations for 2145-SV1 nodes. Important:  With 12 or more ports per node, four ports should be dedicated for  node-to-node traffic. Doing so is especially important when high write data rates are  expected because all writes are mirrored between I/O Group nodes over these ports. The port designation patterns shown in the tables provide the required traffic isolation and  simplify migrations to configurations with greater number of ports. More complicated port  mapping configurations that spread the port traffic across the adapters are supported and can  be considered. However, these approaches do not appreciably increase availability of the  solution.  Alternative port mappings that spread traffic across HBAs might allow adapters to come back  online following a failure. However, they do not prevent a node from going offline temporarily  to restart and attempt to isolate the failed adapter and then rejoin the cluster. Also, the mean time between failures (MTBF) of the adapter is not significantly shorter than  that of the non-redundant node components. The presented approach takes all of these  considerations into account with a view that increased complexity can lead to migration  challenges in the future, and a simpler approach is usually better. You can use a port mask to control the node target ports that a host can access. Using local  FC port masking, you can set which ports can be used for node-to-node/intracluster  communication. Using remote FC port masking, you can set which ports can be used for  replication communication. Port masking, combined with zoning, enables you to dedicate ports to a particular type of  traffic. Setting up Fibre Channel port masks is particularly useful when you have more than  four Fibre Channel ports on any node in the system because it saves setting up many SAN  zones. 66  Implementing the IBM System Storage SAN Volume Controller with IBM Spectrum Virtualize V8.2.1 3.6.8 Port masking Figure 3-15 Port designation recommendations for isolating traffic on 2145-SV1 nodes