Which RAID implementation uses a discrete RAID controller card?

The implementation that uses a discrete RAID controller card is hardware RAID. In hardware RAID, the RAID function is managed by a dedicated hardware card that includes its own processor and memory. This allows for efficient management and processing of data across the drives in the RAID array, which can lead to improved performance and reliability.

Using a hardware RAID controller can also offload the processing tasks that would otherwise be handled by the system's main CPU, freeing up resources for other operations. Additionally, hardware RAID often supports a wider range of RAID levels and features such as battery-backed cache, which enhances data protection and speed.

In contrast, software RAID relies on the operating system to manage the RAID configuration, typically using the system’s CPU for processing, which can limit performance for data-intensive applications. Hybrid RAID employs both hardware and software techniques, while online RAID is not a standard term used to describe RAID implementations.