RAID Card

RAID controllers (and HBAs for non-RAID pass-through) manage how multiple drives combine into logical volumes. Hardware RAID cards offload parity calculation from the host CPU and typically include a cache with battery or flash backup, protecting in-flight writes from power loss — an important consideration for RAID 5/6 arrays, where a write hole without cache protection can cause data loss on unexpected power failure. Software RAID avoids the extra hardware cost but consumes host CPU cycles and does not offer the same write-cache protection. Match the controller's supported RAID levels and drive interface (SAS/SATA/NVMe) to your chosen drives before ordering, and confirm cache battery/capacitor health if buying a refurbished card.