HardwareRAID

Hardware RAID is a disk array management approach that uses a dedicated controller to perform RAID calculations, manage parity, and present a single logical disk to the host system. The controller, typically a PCIe expansion card or an embedded component in a storage enclosure, contains its own processor and memory and often includes cache memory that can be battery-backed or flash-backed. It supports various drive interfaces such as SATA, SAS, or NVMe and can perform writes and rebuilds independently of the host CPU.

Compared with software RAID, hardware RAID offloads processing from the host operating system and can offer more predictable performance and simpler multi-drive management. However, it introduces dependency on a specific controller and firmware; data access can be tied to the vendor, and recovery after controller failure may require compatible hardware or vendor tools. Most hardware controllers present a standard logical unit to the OS, with management through vendor software or interfaces.

Common RAID levels include 0, 1, 5, 6, and 10, with higher-level protections like RAID 50 or RAID 60 available on some controllers. Features often include hot spares, online capacity expansion, and rebuild assistance; cache can be enabled in write-back or write-through mode. Considerations when choosing hardware RAID include cost, vendor lock-in, compatibility with future controllers, and the risk of data loss during rebuilds if multiple drives fail or unrecoverable errors occur. For critical systems, a robust backup strategy remains essential regardless of RAID type.