NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 4x 10TB in RAID 6. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
40.00 TB
Usable Capacity
18.00 TB
Fault Tolerance
2 drives
Efficiency
50.0%
Safer for larger arrays with dual parity, at the cost of one extra parity disk. This scenario applies a 10% filesystem reserve.
Run Interactive Calculator →| Mode | Usable | Tolerance | Efficiency |
|---|---|---|---|
| RAID 5 | 27.00 TB | 1 drive | 75.0% |
| RAID 6 | 18.00 TB | 2 drives | 50.0% |
| RAID 10 | 18.00 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 27.00 TB | 1 drive | 75.0% |
| RAID-Z2 | 18.00 TB | 2 drives | 50.0% |
This setup can tolerate 2 drives. Real-world survivability depends on mirror placement, rebuild stress, and drive health.
It can be practical, but larger drives increase rebuild windows. Validate parity choice and backup policy before committing to the final layout.
No. Use this page for pre-purchase sizing, then validate with workload benchmarks, SMART health policy, and a tested restore plan.
This NAS planning scenario estimates 18.00 TB usable after a 10% reserve from 40.00 TB raw.