Zoning requirements for N_Port ID virtualization
More layout and zoning requirements are necessary for an NPIV configuration in comparison to Fibre Channel host attachment without NPIV. These requirements follow from the fact that NPIV port failover between nodes must be transparent to hosts. Hence, the set of host ports on which an NPIV port is visible cannot change as a result of a failover.
New systems that are installed with version 8.2.0 or later have N_Port ID Virtualization (NPIV) enabled as the default status. If an existing system is updated to version 8.2.0, it retains the NPIV status of the existing system.
The port ID of a virtual port remains constant regardless of the node that it is active on. All of the N_Port IDs for the two nodes in an I/O group must be associated with the same fabric. Ports of the two nodes in an I/O group must be attached to the same fabric, while ports of different I/O groups can be on different fabrics. Figure 1 shows a configuration that is not valid when using NPIV.
The connections to switch ports S2, S4, and S5 must be exchanged, leading to the following correct configuration that is shown in Figure 2.
The same situation can occur when using a single switch fabric with hard (port based) zoning, as shown in Figure 3.
Two nodes are connected to one host by using one switch. However, port-based zoning is used to ensure that each port of the host can detect only one port of each node. S1, S4, and S5 are in one zone; and S2, S3, and S6 are in the other zone.
During an IP failover, NPIV ports move from C1 to C3 and C2 to C4 (or the other way around). The configuration is not valid with NPIV as the visibility of ports move between H1 and H2. To use port-based zoning in this situation, two zones are required: One zone contains S1, S3, S5, C1 and C3. Another zone contains S2, S4, S6, C2 and C4. This configuration is shown in Figure 4.
This situation does not arise when using a single switch fabric with soft (WWPN based) zoning. However, care needs to be taken in a multiswitch fabric where the node-to-host route passes through different switches for the two nodes in an I/O group.
If fabric changes are required, make them before you switch each I/O group to transitional state. I/O groups are switched to transitional state to help move them to NPIV. In transitional state, an I/O group contains both physical and virtual Fibre Channel ports that are currently being used. After you switch to transitional state, an attempt is made by the system software to warn about mismatched fabric issues. It does not warn about issues that are caused by port-based zoning.
Failure to adhere to the fabric zoning rules might cause undesirable behavior on the host during NPIV port failure. Examples include a 2-minute pause in I/O or reduced path redundancy.