What component is required to connect multiple servers to a SAN?

The correct choice is the Host Bus Adapter (HBA). An HBA is a crucial component in connecting servers to a Storage Area Network (SAN). It serves as the interface between the server and the SAN, facilitating the transmission of data over the network. The HBA converts the server's input/output operations into the protocol used for communication with the storage devices in the SAN, such as Fibre Channel or iSCSI.

By enabling direct connections to the SAN, HBAs allow servers to access shared storage resources. This is essential in environments where multiple servers need to access the same storage pool, making it a fundamental part of SAN architectures.

A router, while used in networking to direct traffic between different networks, does not connect servers directly to a SAN. A RAID controller is responsible for managing disk drives within a single server or across a group of disks for redundancy and performance but does not handle the connection to a SAN. A fiber switch, which is used in Fibre Channel SANs to manage and route data traffic between multiple devices, also plays a role but is not directly responsible for connecting servers to the SAN like an HBA does.