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4x 14TB RAID-Z1 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 4x 14TB in RAID-Z1. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

56.00 TB

Usable Capacity

37.80 TB

Fault Tolerance

1 drive

Efficiency

75.0%

ZFS single-parity equivalent of RAID 5; common for smaller homelab pools. This scenario applies a 10% filesystem reserve.

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Alternative Mode Comparison

Mode Usable Tolerance Efficiency
RAID 5 37.80 TB 1 drive 75.0%
RAID 6 25.20 TB 2 drives 50.0%
RAID 10 25.20 TB 1 drive per mirror pair* 50.0%
RAID-Z1 37.80 TB 1 drive 75.0%
RAID-Z2 25.20 TB 2 drives 50.0%

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FAQ

Should I optimize this 4-drive plan for capacity or resiliency first?

For long-lived NAS pools, resiliency first is usually safer. Capacity can be expanded later, while a risky parity choice can force migration sooner.

Can this calculator replace real-world benchmark and rebuild testing?

No. Use this page for pre-purchase sizing, then validate with workload benchmarks, SMART health policy, and a tested restore plan.

Is RAID-Z1 still practical with 14TB drives?

It can be practical, but larger drives increase rebuild windows. Validate parity choice and backup policy before committing to the final layout.

How much effective storage does 4x 14TB RAID-Z1 provide?

This NAS planning scenario estimates 37.80 TB usable after a 10% reserve from 56.00 TB raw.