Which of the following offers the highest level of redundancy in the design of a storage system?

A Dual Port HBA with point-to-point connections bypasses switches but still relies on a single HBA card, making the HBA itself a single point of failure.

Two single-port HBAs eliminate HBA redundancy issues but rely on a single fiber switch, which becomes a single point of failure for the entire fabric.

A single Dual Port HBA with a single point-to-point SAN connection provides no HBA redundancy and no switch redundancy, offering the lowest redundancy of the options.

Two Dual Port HBAs provide four independent host paths, and connecting them to two separate fiber switches creates fully redundant fabric paths with no single point of failure. If one HBA fails, the second HBA still provides two active paths; if one switch fails, the other switch maintains connectivity. This multi-pathing across dual HBAs and dual switches is the highest achievable redundancy level in a SAN design.