NAS pSEO Landing
Region Focus · APAC
Estimate usable TB, parity, and fault tolerance for APAC homelab buyers using 4x 12TB in RAID-Z2.
Raw Capacity
48.00 TB
Usable Capacity
21.60 TB
Fault Tolerance
2 drives
Efficiency
50.0%
Popular TrueNAS default for medium arrays; dual-parity with good safety margin. 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% |
APAC builders frequently compare availability windows and procurement variance, which makes robust fallback capacity and staged scaling useful in practice.
Regional differences in disk availability and replacement lead times.
Policy of keeping spare disks available to reduce recovery delay risk.
For APAC homelab buyers, this NAS planning scenario estimates 21.60 TB usable after a 10% reserve from 48.00 TB raw.
Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.
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.