Server RAID Controllers — Dell PERC, HP Smart Array & LSI Guide for 2026
Complete guide to server RAID controllers. Dell PERC H730 vs HP Smart Array P440 vs LSI MegaRAID. RAID levels, cache modules, battery backup, and compatibility.
What Does a RAID Controller Do?
A RAID (Redundant Array of Independent Disks) controller manages multiple physical drives and presents them to the server operating system as one or more logical volumes. It handles data striping, mirroring, and parity calculations in hardware — offloading this work from the CPU and providing drive redundancy so your data survives a disk failure.
Every enterprise server ships with a RAID controller. Whether you are replacing a failed controller, upgrading for more cache or faster SAS speeds, or building a new server, choosing the right RAID controller is critical for storage performance and data protection.
RAID Levels Explained
| RAID Level | Min Drives | Usable Capacity | Fault Tolerance | Performance | Best For |
|---|---|---|---|---|---|
| RAID 0 | 2 | 100% | None | Fastest | Temporary data only |
| RAID 1 | 2 | 50% | 1 drive failure | Good read | Boot drives, OS |
| RAID 5 | 3 | (N-1)/N | 1 drive failure | Good read, slow write | General storage |
| RAID 6 | 4 | (N-2)/N | 2 drive failures | Good read, slower write | Large arrays |
| RAID 10 | 4 | 50% | 1 per mirror | Best overall | Databases, VMs |
| RAID 50 | 6 | Varies | 1 per span | High throughput | Large datasets |
| RAID 60 | 8 | Varies | 2 per span | High throughput + safety | Enterprise storage |
Pro Tip: For most server workloads, RAID 10 provides the best combination of performance and reliability. Use RAID 6 only when you need maximum usable capacity from many drives and can accept slower write performance.
Dell PERC RAID Controllers
| Model | SAS Speed | Cache | Max Drives | PCIe | Gen |
|---|---|---|---|---|---|
| PERC H310 | 6Gbps | None (HBA mode) | 32 | PCIe 2.0 x8 | 12th-13th |
| PERC H710 | 6Gbps | 512MB / 1GB | 32 | PCIe 2.0 x8 | 12th |
| PERC H730 | 12Gbps | 1GB | 32 | PCIe 3.0 x8 | 13th |
| PERC H730P | 12Gbps | 2GB | 32 | PCIe 3.0 x8 | 13th |
| PERC H740P | 12Gbps | 8GB | 64 | PCIe 3.1 x8 | 14th |
| PERC H755N | 12Gbps | 8GB | 64 | PCIe 4.0 x8 | 15th |
The PERC H730P is the most popular Dell RAID controller on the secondary market. Its 2GB cache provides excellent write-back performance for VMware datastores and database workloads. The H740P doubled cache to 8GB and added SSD caching support for 14th generation servers.
Dell PERC Mini-Mono vs Adapter
Dell offers PERC controllers in two form factors:
- Mini-Mono — Installs in a dedicated motherboard slot (saves a PCIe slot)
- Adapter — Standard PCIe card (for additional controllers or external enclosures)
Always check your server's supported PERC form factor before ordering.
HP Smart Array RAID Controllers
| Model | SAS Speed | Cache | Max Drives | PCIe | Gen |
|---|---|---|---|---|---|
| P420i | 6Gbps | 512MB-2GB | 50 | Integrated | Gen8 |
| P440ar | 12Gbps | 2GB | 28 | Integrated | Gen9 |
| P840 | 12Gbps | 4GB | 64 | PCIe 3.0 x8 | Gen9 |
| E208i-p | 12Gbps | None (HBA mode) | 14 | PCIe 3.0 x8 | Gen10 |
| P408i-a | 12Gbps | 2GB | 26 | Integrated | Gen10 |
| P816i-a | 12Gbps | 4GB | 26 | Integrated | Gen10 |
HP Smart Array controllers use FBWC (Flash-Backed Write Cache) instead of traditional battery-backed cache. FBWC stores cached data to flash memory during power loss, eliminating the need for battery replacement every 2-3 years.
LSI / Broadcom MegaRAID Controllers
LSI (now Broadcom) MegaRAID controllers are brand-agnostic and work in any server with a standard PCIe slot. They are the go-to choice for whitebox servers, Supermicro, and custom builds.
| Model | SAS Speed | Cache | Max Drives | PCIe |
|---|---|---|---|---|
| 9260-8i | 6Gbps | 512MB | 32 | PCIe 2.0 x8 |
| 9271-8i | 6Gbps | 1GB | 32 | PCIe 3.0 x8 |
| 9361-8i | 12Gbps | 1GB | 32 | PCIe 3.0 x8 |
| 9460-8i | 12Gbps | 2GB | 32 | PCIe 3.1 x8 |
| 9560-8i | 12Gbps | 4GB | 32 | PCIe 4.0 x8 |
Key Takeaway: The LSI 9361-8i is the most versatile 12Gbps RAID controller available. It works in Dell, HP, Supermicro, and any standard server, supports RAID 0/1/5/6/10/50/60, and costs $50-80 refurbished.
Cache Module and Battery Backup
RAID controllers with write-back cache dramatically improve write performance by acknowledging writes immediately and flushing to disk in the background. However, cached data is lost during unexpected power loss unless protected by:
- BBU (Battery Backup Unit) — Used by Dell PERC and LSI. Batteries degrade and need replacement every 2-3 years (~$15-30).
- FBWC (Flash-Backed Write Cache) — Used by HP Smart Array. Capacitor powers flash save during power loss. No battery to replace — lasts the life of the controller.
- Supercap — Used by newer Dell PERC (H730P+) and LSI controllers. Capacitor backs up cache to NAND flash. More reliable than traditional batteries.
Without a working cache protector, the controller falls back to write-through mode — every write goes directly to disk, reducing write performance by 50-80%.
RAID Controller vs HBA (IT Mode)
An HBA (Host Bus Adapter) in IT mode passes drives directly to the OS without RAID. This is required for:
- TrueNAS / ZFS — ZFS manages its own redundancy and needs direct drive access
- Ceph — Distributed storage requires individual drive access
- Software RAID — mdadm or Windows Storage Spaces
Popular HBA options: Dell PERC H310 (flashed to IT mode), LSI 9207-8i, LSI 9300-8i.
Pro Disk Network stocks Dell PERC, HP Smart Array, and LSI MegaRAID controllers with cache modules, batteries, and cables included. Every controller is tested with full RAID build verification before shipping. Contact sales@prodisknetwork.com for RAID controller compatibility assistance.