Which drives to run in fnOS
fnOS publishes no per-drive list, so compatibility is a drive-class question, not a part-number question. The rule: CMR for any parity (RAID/ZFS) pool, high-endurance for write-heavy workloads, a small SSD for the system partition, and a second drive (or cloud) for a 3-2-1 cold copy. The ranking below is "most-validated across the five official HCLs we track" — the same drives a Synology or QNAP user would trust, which is the closest proxy fnOS has for a whitelist.
Recommended drive classes for fnOS
| Role | What to buy | Why |
|---|---|---|
| Pool (RAID/ZFS) | CMR NAS/enterprise — IronWolf, Red Plus, Red Pro, N300, Exos | Parity rebuilds and ZFS resyncs are long sustained writes; SMR drives throttle once their cache fills. Always verify in the SMR/CMR checker. |
| Write-heavy / 24-7 | High-endurance or enterprise line | Cameras, logging, containers writing round-the-clock want endurance-rated media, not desktop drives. |
| System / cache | Small (≤512 GB) consumer or datacenter SSD | fnOS keeps its OS partition on a dedicated small SSD — cheaper and more reliable than carving it off a data drive. |
| 3-2-1 cold copy | A second, cheap CMR drive kept offline | Rotating offline copies are the only thing that survives a ransomware that mounted your NAS. See 3-2-1 for NAS. |
Most-validated NAS-class drives (ranked by official HCL coverage)
These are the drives our five vendor HCLs list most often — the safest bet on a system with no whitelist of its own. Open any part number for its full compatibility list.
| Drive | Class | Listed on (official HCLs) |
|---|---|---|
| Toshiba MG04ACA400E · CMR | Enterprise | 451 machines across the HCLs we track |
| Western Digital WD1005VBYZ · CMR | Enterprise | 451 machines across the HCLs we track |
| Western Digital WD2005VBYZ · CMR | Enterprise | 451 machines across the HCLs we track |
| Toshiba MG04ACA300E · CMR | Enterprise | 418 machines across the HCLs we track |
| Toshiba MG04ACA200E · CMR | Enterprise | 416 machines across the HCLs we track |
| Toshiba MG05ACA800E · CMR | Enterprise | 393 machines across the HCLs we track |
| Western Digital WD4003FFBX · CMR | Enterprise NAS | 390 machines across the HCLs we track |
| Seagate ST6000NM021A · CMR | Enterprise | 389 machines across the HCLs we track |
| Toshiba MG04ACA600E · CMR | Enterprise | 382 machines across the HCLs we track |
| Seagate ST1000NM0008 · CMR | Enterprise | 381 machines across the HCLs we track |
| Western Digital WD121KRYZ · CMR | Enterprise | 381 machines across the HCLs we track |
| Seagate ST4000NE0015 · CMR | Enterprise NAS | 379 machines across the HCLs we track |