NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 8x 4TB in RAID 10. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
32.00 TB
Usable Capacity
14.40 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 | 25.20 TB | 1 drive | 87.5% |
| RAID 6 | 21.60 TB | 2 drives | 75.0% |
| RAID 10 | 14.40 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 25.20 TB | 1 drive | 87.5% |
| RAID-Z2 | 21.60 TB | 2 drives | 75.0% |
Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.
This NAS planning scenario estimates 14.40 TB usable after a 10% reserve from 32.00 TB raw.
This setup can tolerate 1 drive per mirror pair*. Real-world survivability depends on mirror placement, rebuild stress, and drive health.
For long-lived NAS pools, resiliency first is usually safer. Capacity can be expanded later, while a risky parity choice can force migration sooner.