NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 12x 18TB in RAID 6. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
216.00 TB
Usable Capacity
162.00 TB
Fault Tolerance
2 drives
Efficiency
83.3%
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 | 178.20 TB | 1 drive | 91.7% |
| RAID 6 | 162.00 TB | 2 drives | 83.3% |
| RAID 10 | 97.20 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 178.20 TB | 1 drive | 91.7% |
| RAID-Z2 | 162.00 TB | 2 drives | 83.3% |
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.
It can be practical, but larger drives increase rebuild windows. Validate parity choice and backup policy before committing to the final layout.
This setup can tolerate 2 drives. Real-world survivability depends on mirror placement, rebuild stress, and drive health.