Hello @BabSimon,
It seems like you posted this a while ago, but I wanted to take a moment to provide a response in case others have a similar question.
The output you shared appears to be from the show flogi database detail command, where two PWWNs are logged into the same interface.
NPIV:
When this occurs, and the interface is connected to either an initiator (host) or a target (storage array), it typically indicates that the device is using N-Port ID Virtualization (NPIV). NPIV is a Fibre Channel standard that allows a single physical Fibre Channel port (N-Port) to register multiple World Wide Names (WWNs) with the fabric. This enables multiple virtual or logical devices to share the same physical port.
Why is NPIV Used?
- Virtualized Server Environments:
NPIV is commonly used in environments with virtualized servers, such as AIX p-Series, VMware, Hyper-V, or other hypervisors. Each virtual machine on the server can have its own unique WWN, even though all traffic flows through a single physical HBA port.
- Storage Arrays:
Some storage vendors use NPIV to facilitate non-disruptive upgrades. For instance, a storage array may use a virtual PWWN to log into the active controller. If the active controller fails, the virtual PWWN is transitioned to the failover controller to maintain connectivity.
- SAN Analytics:
NPIV can provide valuable insights when combined with features such as SAN Analytics. SAN Analytics allows you to monitor metrics like throughput, IOPS, and execution times between two PWWNs.
For example, in an AIX VIOS (Virtual I/O Server) environment, a single interface might host up to 18 virtual Fibre Channel HBAs (vHBAs). If the interface bandwidth becomes saturated, identifying which LPAR (Logical Partition) is consuming the most I/O was historically challenging. However, with SAN Analytics, you can pinpoint the specific vHBA and the LPAR it belongs to. This information helps AIX administrators notify application owners of bandwidth overuse and take corrective actions.
I hope this explanation helps!
