RAID Controller Guide: PERC, Smart Array, and MegaRAID Explained
Understanding RAID controllers in Dell (PERC), HP (Smart Array), and generic (MegaRAID) servers. Learn about RAID levels, cache, BBU, and how to choose the right controller for your storage needs.
What Is a RAID Controller and Why Does It Matter?
A RAID controller is a hardware card or chip that manages multiple hard drives or SSDs as a single logical unit. It handles data striping, mirroring, and parity calculations so your operating system sees one fast, reliable volume instead of individual disks. Without a RAID controller, a single drive failure can mean total data loss.
RAID Levels You Actually Need to Know
Skip RAID 2, 3, and 4. In 2026, these are the RAID levels that matter:
RAID 0 (Striping): Data split across drives for maximum speed. Zero redundancy. If any drive fails, all data is lost. Use only for temporary scratch space or test environments where data loss is acceptable.
RAID 1 (Mirroring): Exact copy of data on two drives. Simple, fast reads, but you lose 50 percent of capacity to redundancy. Best for boot drives and small critical databases.
RAID 5 (Striping + Parity): Data and parity distributed across 3+ drives. Survives one drive failure. Good read performance but slow writes due to parity calculation. Use for file servers and read-heavy workloads.
RAID 6 (Double Parity): Like RAID 5 but survives two simultaneous drive failures. Requires 4+ drives. The standard choice for large arrays with spinning disks where rebuild times are long.
RAID 10 (1+0): Combination of mirroring and striping. Requires 4+ drives, loses 50 percent to mirroring, but delivers the best performance and reliability. The gold standard for databases and virtualization.
Dell PERC Controllers
PERC (PowerEdge RAID Controller) is Dell's branded line of RAID controllers. Current and recent generations:
- PERC H330: Entry-level, no cache. Basic RAID 0/1/5/10. Good for boot drives.
- PERC H730: 1GB or 2GB cache with BBU. RAID 0/1/5/6/10/50/60. The workhorse for most PowerEdge servers.
- PERC H740P: 8GB cache with flash-backed protection. High-performance for SSD arrays.
- PERC H755: Latest generation for 15th Gen PowerEdge. PCIe Gen4, NVMe support.
HP Smart Array Controllers
Smart Array is HP's RAID controller line for ProLiant servers:
- P222: Entry-level, 512MB cache. SAS 6Gbps. For Gen8 servers.
- P440ar: 2GB cache with FBWC. SAS 12Gbps. The default in DL380 Gen9.
- P408i-a: 2GB cache with smartcache SSD support. For Gen10 servers.
- E208i-a: Entry-level for Gen10. No cache, software RAID only.
- MR416i-a: Latest Gen11 controller. Tri-mode (SAS/SATA/NVMe).
Broadcom MegaRAID (Generic)
For non-Dell, non-HP servers (Supermicro, custom builds), Broadcom MegaRAID controllers are the industry standard:
- MegaRAID 9460-8i: 8 ports, 2GB cache, SAS/SATA/NVMe tri-mode.
- MegaRAID 9560-8i: Latest gen, 8GB cache, PCIe Gen4, tri-mode.
Cache and Battery Backup
RAID controller cache dramatically improves write performance by buffering writes before committing them to disk. But if the server loses power during a cached write, data can be lost or corrupted.
Battery Backup Unit (BBU): Older solution. A rechargeable battery keeps the cache alive during power loss. Batteries degrade over 2-3 years and must be replaced.
Flash-Backed Write Cache (FBWC/Capacitor): Modern solution. A supercapacitor holds power long enough to flush the cache to onboard flash memory. No battery degradation. This is what you want in 2026.
Buying Tips
Always match the RAID controller generation to your server generation. A PERC H730 from a 13th Gen PowerEdge will not work in a 15th Gen server. The connector, firmware, and BIOS integration are generation-specific.
Pro Disk Network stocks over 2,400 RAID controllers across Dell PERC, HP Smart Array, and Broadcom MegaRAID families. Every controller is tested and verified compatible with specific server models. Search by part number or server model at prodisknetwork.com.