Introduction
One of the most frequently debated topics in enterprise storage is whether to use a hardware RAID controller or an HBA (Host Bus Adapter) in IT Mode. The answer depends entirely on your operating system and storage architecture — and getting it wrong can lead to data loss, poor performance, or incompatibility.
This guide cuts through the confusion and gives you a clear decision framework for ZFS, TrueNAS, Proxmox, VMware, and Windows Server environments.
The Core Difference
The fundamental difference between an HBA and a RAID controller comes down to who manages the drives:
- HBA (IT Mode): The card passes drives directly to the OS. The OS sees each physical drive individually and manages storage in software.
- RAID Controller: The card manages drives in hardware, presenting logical volumes (virtual disks) to the OS. The OS sees only the RAID volume, not the individual drives.
When to Use an HBA
Use an HBA in IT Mode when your OS or storage platform manages storage in software:
- TrueNAS (CORE or SCALE): ZFS requires direct access to physical drives. Never use a hardware RAID controller with ZFS — it prevents ZFS from detecting drive failures and performing self-healing.
- Proxmox with ZFS: Same rule applies. Use an HBA so Proxmox ZFS can see and manage each drive directly.
- Linux with mdadm or ZFS: Software RAID requires raw drive access.
- JBOD expansion: Connecting a JBOD shelf to a server requires an HBA, not a RAID controller.
Recommended HBA cards: LSI 9300-8i, 9300-16i, 9400-8i, 9500-8i, 9500-16i (all in IT Mode firmware).
When to Use a Hardware RAID Controller
Use a hardware RAID controller when the OS should not manage storage directly:
- Windows Server: Hardware RAID simplifies storage management and provides cache-backed write performance with BBU or CacheVault protection.
- VMware ESXi: Hardware RAID presents a clean logical volume to the hypervisor, simplifying datastore management.
- Legacy applications: Some enterprise applications expect hardware RAID and do not support software-defined storage.
- High write workloads: RAID controllers with onboard cache (2GB–4GB) and CacheVault protection deliver significantly higher write IOPS than software RAID.
Recommended RAID controllers: Broadcom MegaRAID 9361-8i, 9460-8i, 9500-16i, 9560-16i.
The IT Mode Firmware Requirement
Many LSI HBA cards ship with IR (Integrated RAID) firmware as shipped by the vendor. For ZFS and TrueNAS use, you must flash the card to IT Mode firmware, which disables the onboard RAID engine and enables pure pass-through operation.
At Zhongxin Data, all HBA cards sold for JBOD/ZFS use are pre-flashed to IT Mode firmware unless otherwise specified. Always confirm firmware mode when ordering.
Tri-Mode Controllers: A Middle Ground
Modern Broadcom Tri-Mode controllers (9400-8i, 9500-16i, 9560-8i) can operate in both RAID and HBA modes depending on firmware configuration. They also support NVMe drives alongside SAS and SATA — making them ideal for mixed storage environments.
Quick Decision Guide
- TrueNAS / ZFS: HBA in IT Mode — always
- Proxmox ZFS: HBA in IT Mode — always
- VMware ESXi: Hardware RAID controller (MegaRAID)
- Windows Server: Hardware RAID controller (MegaRAID)
- Mixed NVMe + SAS/SATA: Tri-Mode controller (9500-16i or 9560-16i)
- JBOD expansion: HBA in IT Mode
Shop HBA and RAID Controllers at Zhongxin Data
Zhongxin Data stocks a full range of Broadcom MegaRAID RAID controllers and LSI HBA cards in IT Mode. All hardware is original original-vendor, fully tested, and firmware-verified before shipment. Worldwide shipping from Hong Kong, China with warranty included.
Contact us for bulk pricing or firmware configuration questions.
What each storage stack wants from the card
- ZFS and TrueNAS want raw drives and manage redundancy themselves — a pass-through HBA is the match
- VMware ESXi supports both, and the choice is usually about management and driver support
- Proxmox with ZFS behaves like ZFS; without it, the choice is mostly operational preference
The failure cases worth knowing before you choose
- A hardware RAID layer can mask media errors that a filesystem would otherwise report and correct
- A failed battery-backed cache drops write-back to write-through, which changes write latency and alerting
- Pass-through removes a layer, so the failure surface is the drives and the enclosure instead
NVMe, tri-mode and the modern build decision
- NVMe needs a tri-mode controller or a dedicated NVMe HBA — SAS-only cards cannot attach NVMe
- A tri-mode card in HBA mode covers SAS, SATA and NVMe in one slot, which simplifies the build
- For an NVMe-only array, an HBA is usually simpler and cheaper than a tri-mode RAID card
Related reading
- MegaRAID 9500-8e tri-mode HBA — the tri-mode pass-through option
- RAID vs HBA guide — the general decision
- Enterprise SSD selection — media selection for the same builds
- RAID controllers — category hub
Frequently Asked Questions
What is the best HBA for TrueNAS?
A plain HBA that passes drives through, with IT mode or no RAID layer. A tri-mode card in HBA mode is the common choice because it covers SAS, SATA and NVMe in one SKU. The key requirement is that the card must not create a virtual disk, because TrueNAS manages redundancy itself. Tell us your drive mix and we will confirm the exact card.
Should I use an HBA or a RAID controller with ZFS?
An HBA, in almost every case. ZFS provides checksumming, scrubbing and its own redundancy, and a hardware RAID layer in front of it removes the visibility ZFS depends on. If you want a single accountable device with cache protection and vendor management, hardware RAID is the alternative — but it is a different philosophy, not a better one.
Does VMware ESXi support pass-through HBA?
Yes. ESXi supports both a hardware RAID controller presenting virtual disks and a pass-through HBA presenting raw devices. vSAN and other software-defined storage tiers specifically want raw access, so an HBA is the usual choice there. For traditional virtual machines with a hardware RAID array, the controller is the supported path.
Can I use a RAID controller in HBA mode for ZFS?
Yes. The tri-mode generation, the 9500 and 9600 families, supports HBA mode where the card passes drives through without a virtual disk. That lets one SKU cover both SAS and NVMe enclosures and keeps the option to change approach later without changing hardware.
What happens if the cache battery fails on a RAID controller?
The controller drops out of write-back mode and continues in write-through, which is slower on writes and changes the alerting you should expect. The data is not lost — it is protected, but the performance profile changes. This is why we test and report the CacheVault supercap status on every used controller we list.
How do you verify a used HBA or RAID controller?
We clean, re-flash and bench-test on our own test line, then confirm the part number, cache size, connector count, port mapping and firmware level, and we read the supercap status on cache-protected models. We report what we find rather than leaving it to be discovered at install time. Ask for photos of the actual card before you commit.