NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 6x 12TB in RAID-Z2. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
72.00 TB
Usable Capacity
43.20 TB
Fault Tolerance
2 drives
Efficiency
66.7%
Popular TrueNAS default for medium arrays; dual-parity with good safety margin. This scenario applies a 10% filesystem reserve.
Run Interactive Calculator →| Mode | Usable | Tolerance | Efficiency |
|---|---|---|---|
| RAID 5 | 54.00 TB | 1 drive | 83.3% |
| RAID 6 | 43.20 TB | 2 drives | 66.7% |
| RAID 10 | 32.40 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 54.00 TB | 1 drive | 83.3% |
| RAID-Z2 | 43.20 TB | 2 drives | 66.7% |
It can be practical, but larger drives increase rebuild windows. Validate parity choice and backup policy before committing to the final layout.
For long-lived NAS pools, resiliency first is usually safer. Capacity can be expanded later, while a risky parity choice can force migration sooner.
No. Use this page for pre-purchase sizing, then validate with workload benchmarks, SMART health policy, and a tested restore plan.
Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.