What is a RAID controller?

• A. Software utility for monitoring temperature.
• B. A module that handles CPU microcode.
• C. A device that powers GPUs.
• D. Host Bus Adapter or hardware RAID that aggregates drives for redundancy/performance.

Answer: (D)

A RAID controller is the hardware that manages a RAID array, sitting between the storage drives and the rest of the system. It handles how data is written across multiple drives, provides redundancy, and can boost performance by striping data and caching. In hardware RAID, a dedicated controller (often a PCIe card known as a host bus adapter with RAID capabilities) processes the RAID logic, parity, and caching, presenting one or more virtual drives to the operating system. This offloads RAID work from the CPU and can include features like battery-backed cache to protect data integrity. That’s why the best description is a Host Bus Adapter or hardware RAID that aggregates drives for redundancy and performance. The other options describe unrelated functions: a temperature-monitoring software utility, a CPU microcode module, or a device that powers GPUs.