In a multi-switch fabric where it is necessary to manually map out preferred paths based on application priority and topology, while still allowing failover to non-preferred paths if needed, Traffic Isolation Zones (TIZs) are the recommended functionality. TIZs provide a mechanism to segregate and control traffic within a Fibre Channel (FC) fabric, ensuring that specific application traffic follows the preferred paths while providing the necessary failover capabilities. This enhances the performance and reliability of critical applications by keeping their traffic on dedicated paths, reducing the risk of congestion and ensuring that failover paths are used only when necessary.
For more details, refer to the following HPE Storage references:
* HPE B-series FC Switches

During the upgrade of the HPE 3PAR StoreServ 8200 to include 4-port 16Gb FC adapters, the Multipath I/O (MPIO) service will handle failover automatically. This ensures that if any of the paths are temporarily unavailable during the upgrade, the servers will still have continuous access to the storage via the remaining paths. MPIO is designed to manage multiple paths and will reroute traffic through available paths, minimizing the impact of the upgrade on storage availability.
Reference:
HPE 3PAR StoreServ MPIO and Availability
HPE 3PAR StoreServ Port Persistence

In HPE GreenLake for Block Storage, VV (Virtual Volumes) and LD (Logical Devices) are owned by a single node. This ownership model is critical for ensuring data consistency and managing the resources effectively across the storage array. By having a single node own the VV LDs, the system can maintain optimal performance and reliability, especially in clustered environments where multiple nodes are involved.