Node configuration details

Apply these configuration details to nodes to ensure that you have a valid configuration.

Host bus adapters and

For information about supported hardware, see the following website: www.ibm.com/support.

Nodes contain a mix of different supported network adapters. For more information about what the system supports, see Optional features.

Volumes

Each node can present a volume (SCSI logical unit) to the SAN through Fibre Channel ports or iSCSI ports. Each volume is accessible from the two nodes in an I/O group. Each host network port can recognize up to eight paths to each logical unit (LU) that is presented by the system. The hosts must run a multipathing device driver before the multiple paths can resolve to a single device. You can use fabric zoning, VLANs, or port masking to reduce the number of paths to a volume that are visible by the host. The network port types are Ethernet (iSCSI) and Fibre Channel.

Optical connections

Valid optical connections are based on the fabric rules that the manufacturers impose for the following connection methods:
  • Host to a switch
  • Back end to a switch.
  • Inter-switch links (ISLs)

Optical fiber connections can be used between a node and its switches.

Systems that use the intersystem Metro Mirror and Global Mirror functions can use optical fiber connections between the switches, or they can use distance-extender technology that is supported by the switch manufacturer.

Ethernet connection

To ensure system management failover operations, Ethernet port 1 on all nodes must be connected to the same set of subnets. If used, Ethernet port 2 on all nodes must also be connected to the same set of subnets. However, the subnets for Ethernet port 1 do not have to be the same as Ethernet port 2.

For host multipathing failover, node iSCSI ports must match between the two nodes in an I/O group.

Fibre Channel connection

The system supports shortwave and longwave Fibre Channel connections between nodes and the switches to which they are connected.

No ISL hops are permitted among the nodes within the same I/O group. However, no more than three ISL hops are permitted among nodes that are in the same system though different I/O groups. If your configuration requires more than three ISL hops for nodes that are in the same system but in different I/O groups, contact your support center.

Avoid communication between nodes and storage systems that are being routed across ISLs. To do so, connect all storage systems to the same Fibre Channel switches as the nodes. One ISL hop between the nodes and the storage systems is permitted. If your configuration requires more than one ISL, contact your support center.

In larger configurations, it is common to have ISLs between host systems and the nodes.

Port speed

Fibre Channel ports on nodes can operate at 16 Gbps, 8 Gbps, and 4 Gbps. The ports are not supported on 2 Gbps speed switches.