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3x 12TB RAID-Z1 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 3x 12TB in RAID-Z1. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

36.00 TB

Usable Capacity

21.60 TB

Fault Tolerance

1 drive

Efficiency

66.7%

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 21.60 TB 1 drive 66.7%
RAID 6 N/A N/A N/A
RAID 10 N/A N/A N/A
RAID-Z1 21.60 TB 1 drive 66.7%
RAID-Z2 N/A N/A N/A

NAS Cluster Guides

NAS Hub RAID Level Compare RAID Capacity Matrix Planning Quick Sheet RAID Selector NAS FAQ

Related Long-Tail Calculators

2x 4TB RAID 1 2x 6TB RAID 1 2x 8TB RAID 1 2x 10TB RAID 1 2x 12TB RAID 1 2x 14TB RAID 1 2x 16TB RAID 1 2x 18TB RAID 1 2x 20TB RAID 1 3x 4TB RAID 1 3x 4TB RAID 5 3x 4TB RAID-Z1 3x 6TB RAID 1 3x 6TB RAID 5 3x 6TB RAID-Z1 3x 8TB RAID 1

Sequential Long-Tail Navigation

← Previous: 3x 12TB RAID 5 NAS Calculator | Usable TB Next: 3x 14TB RAID 1 NAS Calculator | Usable TB →

FAQ

Is RAID-Z1 still practical with 12TB 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 3x 12TB RAID-Z1 provide?

This NAS planning scenario estimates 21.60 TB usable after a 10% reserve from 36.00 TB raw.

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.

Why include a 10% reserve when planning NAS available space?

Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.