A server has a faulty hard drive, and the administrator needs to replace the hard drive while it is running. The server needs to support which of the following drives?

Hot swappable drives are engineered to be inserted or removed from a running system without requiring a shutdown or restart. The server's backplane, controller, and operating system all support live drive detection and removal, allowing the replacement to occur while services remain active. This capability is essential in enterprise servers where any downtime for disk replacement is unacceptable.

A hot spare is a pre-installed standby drive that automatically assumes the role of a failed drive, but it is the failover mechanism - not the drive that the administrator physically swaps out.

SAS is a storage interface standard that can support hot swap, but the interface type alone does not guarantee hot swap capability - it requires a compatible backplane and server configuration.

USB is an external peripheral interface not used for primary server storage, and USB drives are not designed for the high-availability, hot-swap storage scenarios described.

FireWire (IEEE 1394) is an external interface designed for peripherals such as cameras and audio devices, not for server hard drive storage requiring online replacement.