Chapter 3. Planning 63
To use these protocols, the system requires that a 25 Gbps Ethernet adapter is installed on 
each node and dedicated RDMA-based ports are only configured for node-to-node 
communication.
RDMA technologies, like RoCE and iWARP, enable the 25 Gbps Ethernet adapter to transfer 
data directly between nodes, bypassing CPU, and caches, making transfers faster. 
RDMA technologies provide faster connection and processing time than traditional iSCSI 
connections and are a lower-cost option than Fibre Channel fabrics.
Prerequisites
The following prerequisites must be met for all RDMA-based connections between nodes:
/SM590000Installation of the node hardware is complete.
/SM590000A 25 Gbps Ethernet adapter is installed on each node.
/SM590000Ethernet cables between each node are connected correctly.
/SM590000Protocols on the source and destination adapters are the same.
/SM590000Local and remote IP addresses can be reached.
/SM590000Each IP address is unique.
/SM590000The negotiated speeds on the local and remote adapters are the same.
/SM590000The local and remote port virtual LAN identifiers are the same.
/SM590000A minimum of two dedicated ports are required for node-to-node RDMA communications 
to ensure best performance and reliability. These ports must be configured for inter-node 
traffic only and cannot be used for host attachment, virtualization of Ethernet-attached 
external storage, or IP replication traffic. 
/SM590000A maximum of four ports per node are allowed for node-to-node RDMA connections. 
Configure a local port mask that limits node-to-node connections to maximum of four ports 
per node. For more information, see this IBM Knowledge Center web page.
3.7.5  iSCSI back-end storage attachment
IBM Spectrum Virtualize V7.7 introduced support for external storage controllers that are 
attached through iSCSI.
For more information about back-end storage supported for iSCSI connectivity, see these 
websites:
/SM590000IBM Support Information for Storwize V7000 
/SM590000IBM System Storage Interoperation Center (SSIC) 
3.8  Back-end storage subsystem configuration
Back-end storage subsystem configuration must be planned for all storage controllers that are 
attached to the Storwize V7000. 
For more information about supported storage subsystems, see these websites:
/SM590000IBM Support Information for Storwize V7000
/SM590000IBM System Storage Interoperation Center (SSIC)