NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 4x 18TB in RAID 5. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
72.00 TB
Usable Capacity
48.60 TB
Fault Tolerance
1 drive
Efficiency
75.0%
Balanced capacity and redundancy, but rebuild stress can be high on large disks. This scenario applies a 10% filesystem reserve.
Run Interactive Calculator →| Mode | Usable | Tolerance | Efficiency |
|---|---|---|---|
| RAID 5 | 48.60 TB | 1 drive | 75.0% |
| RAID 6 | 32.40 TB | 2 drives | 50.0% |
| RAID 10 | 32.40 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 48.60 TB | 1 drive | 75.0% |
| RAID-Z2 | 32.40 TB | 2 drives | 50.0% |
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. 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.
This NAS planning scenario estimates 48.60 TB usable after a 10% reserve from 72.00 TB raw.