IT-mode HBAs for ZFS, TrueNAS and Unraid
Which SAS HBA to buy for a ZFS, TrueNAS or Unraid build: IT vs IR mode, the LSI chipset generations (SAS2008 to SAS3416), every common card and OEM rebrand, and what to buy for HDDs, SSDs and big pools.
Once a NAS outgrows the handful of SATA ports on its motherboard, the fix is a SAS host bus adapter. Get the right one and it disappears into the build: every disk shows up to the OS directly, SMART works, and ZFS owns the array like it should. Get the wrong one - a RAID card left in RAID mode - and you spend a weekend fighting phantom failures. This is how to pick the right card the first time, across every chipset and every cheap OEM rebrand worth buying.
What an HBA is, and IT vs IR mode
A host bus adapter is a plain disk controller. No RAID, no volume management, no cache doing things behind your back. It presents each drive to the operating system as its own device. That is exactly what ZFS, TrueNAS and Unraid want, because those systems are the volume manager - they schedule writes, checksum data and read SMART to predict failures. A RAID layer sitting underneath just gets in the way.
LSI SAS cards run one of two firmwares:
- IT (Initiator Target) turns the card into a pure pass-through HBA. Raw disks, full SMART, no RAID. This is the mode you want.
- IR (Integrated RAID) adds a light onboard RAID layer (RAID 0/1/1E). Same chip, same ports, but now the firmware inserts itself between your disks and the OS.
For anything running ZFS, use IT. IR is only fine when a RAID-aware filesystem is nowhere near the card. Many cards ship in IR or full RAID mode and have to be flashed to IT first - which is a whole procedure of its own, covered in how to crossflash any LSI SAS HBA to IT mode.
The chipset generations
Almost every HBA a home NAS builder will meet is an LSI/Broadcom design. The chip decides the speed, the PCIe bandwidth and the number of ports. Everything else is branding.
| Chipset | SAS gen | PCIe | Typical ports | Best for |
|---|---|---|---|---|
| SAS2008 | 6Gb/s | 2.0 x8 | 8 | HDD pools, cheapest entry |
| SAS2308 | 6Gb/s | 3.0 x8 | 8 | HDDs plus SATA SSDs (more host bandwidth) |
| SAS3008 | 12Gb/s | 3.0 x8 | 8 | SAS3 SSDs, modern builds |
| SAS3216 / SAS3224 | 12Gb/s | 3.0 x8 | 16 / 24 | Big single-card arrays, no expander |
| SAS3416 | 12Gb/s (tri-mode) | 3.1 x8 | 16 | SAS, SATA and NVMe on one card |
The thing to understand: for spinning disks, even the ancient SAS2008 is plenty. Eight HDDs share a PCIe 2.0 x8 link (around 4 GB/s) and no hard drive array will ever come close to filling that. You only need the newer generations when you're running SSDs, where the extra host bandwidth and 12Gb/s per port actually get used.
The card landscape (genuine and rebranded)
The chip matters, not the sticker. A given chipset ships as a genuine LSI card and as a pile of OEM rebrands from Dell, IBM/Lenovo and HP that cost a fraction on the used market and flash to the exact same thing.
- SAS2008: genuine LSI 9211-8i and 9211-4i. Rebrands: IBM M1015, Dell H310, Dell H200. All flash to 9211-8i IT.
- SAS2308: genuine LSI 9207-8i (IT-only) and 9217-8i (IR). Rebrand: HP H220 (= 9205-8i). Flash to 9207-8i IT.
- SAS3008: genuine LSI 9300-8i and the dual-chip 9300-16i. Rebrands: Dell HBA330 (ships IT already), Dell H330 (RAID), Lenovo N2215. Flash to 9300-8i IT, or the HBA330 which needs no flash at all.
- SAS3216 / SAS3224: LSI 9305-16i and 9305-24i - single-chip, high-port, native IT.
- SAS3416: LSI 9400-16i - tri-mode, native IT.
Every one of these, with its ports, firmware and crossflash status, is in the IT-mode HBA reference table. The short version of who needs flashing: the RAID-branded rebrands (M1015, H310, H200, H220, H330, N2215) ship in RAID/IR and need a crossflash; the IT-SKU cards (9211-8i, 9207-8i, 9300-8i) and the Dell HBA330 are ready out of the box.
What to actually buy
Match the card to the workload, not to the newest chip.
- Cheapest HDD pool: a flashed LSI 9211-8i or an IBM M1015 for a few dollars. Bulletproof, and every ZFS guide on earth assumes it. You do the crossflash yourself.
- Skip the flash: a Dell HBA330. It ships IT from Dell, it's SAS3, and it's cheap used. No DOS, no
sas3flash, no afternoon lost. This is the one I recommend to anyone who doesn't want a project. - SATA/SAS SSD array: a 9207-8i (PCIe 3.0 doubles host bandwidth vs the 9211) or a 9300-8i for 12Gb/s.
- Big pool, one card: a 9305-16i or 9305-24i. Single chip, 16 or 24 ports, no expander needed.
- NVMe/U.2 or future-proofing: a 9400-16i tri-mode. Overkill for HDDs, but it speaks SAS, SATA and NVMe.
For most home builds an 8-port card covers it. Past eight drives you either step up to a 16i card or add a SAS expander, which is its own topic - see SAS cables, connectors and expanders.
Two things people get wrong
RAID cards are not HBAs. A Dell H730 (SAS3108) or an HP Smart Array P420 is a hardware RAID controller, not a pass-through card, and there's no clean path to IT mode. Don't buy one for ZFS hoping to flash it. Buy a real HBA.
Airflow is not optional. These are datacenter cards built for 200+ LFM of forced air. In a quiet tower they run hot and throw errors that look exactly like a dying disk or a bad flash. Zip-tie a 40mm fan to the heatsink and the mystery failures vanish.
That's the whole decision. Pick the chip that matches your disks, buy the cheapest card that carries it, flash it to IT if it needs it, and give it air. The HBA reference has the specs for every card, and the crossflash guide walks through turning a cheap RAID card into a proper HBA.