NAS pSEO Landing
Region Focus · US
Estimate usable TB, parity, and fault tolerance for US homelab buyers using 4x 12TB in RAID 6.
Raw Capacity
48.00 TB
Usable Capacity
21.60 TB
Fault Tolerance
2 drives
Efficiency
50.0%
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 | 32.40 TB | 1 drive | 75.0% |
| RAID 6 | 21.60 TB | 2 drives | 50.0% |
| RAID 10 | 21.60 TB | 1 drive per mirror pair* | 50.0% |
| RAID-Z1 | 32.40 TB | 1 drive | 75.0% |
| RAID-Z2 | 21.60 TB | 2 drives | 50.0% |
US buyers often evaluate frequent pricing swings and promo cycles. Capacity planning should account for staged purchases instead of one-time all-disk upgrades.
Planning metric that compares real usable capacity after reserve and parity.
Seasonal pricing period used for phased drive purchasing strategies.
For long-lived NAS pools, resiliency first is usually safer. Capacity can be expanded later, while a risky parity choice can force migration sooner.
This setup can tolerate 2 drives. 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.
Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.