NAS pSEO Landing
Estimate usable TB, parity overhead, and fault tolerance for 12x 4TB in RAID-Z1. Includes reserve planning for NAS and homelab arrays.
Raw Capacity
48.00 TB
Usable Capacity
39.60 TB
Fault Tolerance
1 drive
Efficiency
91.7%
ZFS single-parity equivalent of RAID 5; common for smaller homelab pools. 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% |
Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.
For long-lived NAS pools, resiliency first is usually safer. Capacity can be expanded later, while a risky parity choice can force migration sooner.
No. Use this page for pre-purchase sizing, then validate with workload benchmarks, SMART health policy, and a tested restore plan.
It can be practical, but larger drives increase rebuild windows. Validate parity choice and backup policy before committing to the final layout.