Zoning and portsets

Ensure that you are familiar with these zoning details and host zones. More details are included in the SAN configuration and zoning rules summary.

Paths to hosts

The number of paths through the network from the node canisters to a host must not exceed eight. Configurations in which this number is exceeded are not supported.

Portset avoids wrong zoning configuration and limits the number of paths though which hosts can access external storage devices. Zoning host ports to too many ports of external system can create redundant paths. Also, unnecessary host login to too many Fibre Channel ports of external system consumes resources and leads to non-uniform distribution of host login on ports. Portsets limit the number of paths that the host can access to external storage system and distributes the host login evenly across multiple ports. For more information on Fibre Channel portsets, refer to the Fibre Channel portset.

Fibre Channel portset is mapped with Fibre Channel port and host object. The host port WWPNs must be zoned only to external system Fibre Channel ports that are associated with the portset. If host ports are zoned to any other Fibre Channel port, the system notifies non-porset member login. Such logins can be removed by switching zones. An administrator can identify such logins by using the lsfabric command. The mkhost command shows host login counts on ports and enable the administrator to identify less loaded portsets. The command also shows the WWPNs that an administrator can use with host ports for zoning.

Adding WWPN to portsets provides greater flexibility and can be used for specific functional use cases. For example, SCSI host WWPN on a Fibre Channel port can be added to Portset1, whereas NVMeFC host WWPN on that port can be added to different portset.

To find the worldwide port names (WWPNs) that are required to set up Fibre Channel zoning with hosts, use the lstargetportfc command. This command also displays the current failover status of host I/O ports.

Host zones

The configuration rules for host zones are different depending upon the number of hosts that access the system. For configurations of fewer than 64 hosts per system, the system supports a simple set of zoning rules that enable a small set of host zones to be created for different environments. For configurations of more than 64 hosts per system, the system supports a more restrictive set of host zoning rules.

Zoning that contains host HBAs must ensure host HBAs in dissimilar hosts or dissimilar HBAs are in separate zones. Dissimilar hosts means that the hosts are running different operating systems or are different hardware products; thus different levels of the same operating system are regarded as similar.

You can map each volume that you create on the system to multiple HBA Fibre Channel ports in a specific host. There can also be multiple paths across the SAN. For these reasons, each host must run multipathing software, such as the Microsoft Device Specific Module (MSDSM). The multipathing software manages the many paths that are available to the volume and presents a single storage device to the operating system. The system supports various multipathing software packages. The specific multipathing software that the system supports depends on the host operating system that you use the software with.

The number of paths through the network from the system nodes to a host must not exceed eight. Configurations that exceed this number are unsupported.

Each system node has multiple ports and each I/O group has two system nodes. Therefore, without any zoning, the number of paths to a volume is the number of system ports in the I/O group times the number of host ports.
This rule exists to limit the number of paths that must be resolved by the multipathing device driver.

If you want to restrict the number of paths to a host, zone the switches so that each HBA port is zoned with one system port for each node in the clustered system. If a host has multiple HBA ports, zone each port to a different set of system ports to maximize performance and redundancy.

To obtain the best overall performance of the system and to prevent overloading, the workload to each port must be equal. This can typically involve zoning approximately the same number of host Fibre Channel ports to each Fibre Channel port.

Systems with fewer than 64 hosts:

For systems with fewer than 64 hosts that are attached, zones that contain host HBAs must contain no more than 40 initiators, including the ports that act as initiators. A configuration that exceeds 40 initiators is not supported. A valid zone can be 32 host ports plus 8 ports. When it is possible, place each HBA port in a host that connects to a node into a separate zone. Include exactly one port from each node in the I/O groups that are associated with this host. This type of host zoning is not mandatory, but is preferred for smaller configurations.

Note: If the switch vendor recommends fewer ports per zone for a particular SAN, the rules that are imposed by the vendor take precedence over system rules.

Systems with more than 64 hosts:

Each HBA port must be in a separate zone and each zone must contain exactly one port from each node in each I/O group that the host accesses.