During Fibre Channel adapter setup of a ESXi host, which configuration guideline should be considered?

The vendor-mixing restriction is the authoritative guideline - a narrower restriction based solely on model differences within a vendor is not what VMware's official FC configuration guidelines specify.

Different vendors implement FC HBA drivers, queue depth management, and error-recovery behavior differently, so mixing vendors in one host can produce inconsistent multipathing behavior, unpredictable I/O performance, and joint-vendor supportability gaps when accessing the same storage targets. VMware's SAN configuration guide explicitly lists single-vendor HBA usage per host as a required configuration guideline.

Actively recommending mixed-vendor FC adapters contradicts VMware's documented best practice, which prohibits this configuration to ensure consistent behavior and support.

VMware does not publish a guideline setting queue depth to 16 for mixed-vendor configurations - queue depth tuning is driven by storage array vendor recommendations, not by adapter vendor mixing.