NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 12x 4TB in RAID 10. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
48.00 TB
Usable Capacity
21.60 TB
Fault Tolerance
1 drive per mirror pair*
Efficiency
50.0%
Excellent random I/O and rebuild behavior; capacity is typically 50% of raw. This scenario applies a 10% filesystem reserve.
Run Interactive Calculator →| Mode | Usable | Tolerance | Efficiency |
|---|---|---|---|
| RAID 5 | 39.60 TB | 1 drive | 91.7% |
| RAID 6 | 36.00 TB | 2 drives | 83.3% |
| RAID 10 | 21.60 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 39.60 TB | 1 drive | 91.7% |
| RAID-Z2 | 36.00 TB | 2 drives | 83.3% |
This NAS planning scenario estimates 21.60 TB usable after a 10% reserve from 48.00 TB raw.
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 setup can tolerate 1 drive per mirror pair*. Real-world survivability depends on mirror placement, rebuild stress, and drive health.