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12x 10TB RAID 1 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 12x 10TB in RAID 1. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

120.00 TB

Usable Capacity

9.00 TB

Fault Tolerance

11 drives*

Efficiency

8.3%

Strong redundancy but low capacity efficiency. Great for small, critical datasets. This scenario applies a 10% filesystem reserve.

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Alternative Mode Comparison

Mode	Usable	Tolerance	Efficiency
RAID 5	99.00 TB	1 drive	91.7%
RAID 6	90.00 TB	2 drives	83.3%
RAID 10	54.00 TB	1 drive per mirror pair*	50.0%
RAID-Z1	99.00 TB	1 drive	91.7%
RAID-Z2	90.00 TB	2 drives	83.3%

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: 12x 8TB RAID-Z2 NAS Calculator | Usable TB Next: 12x 10TB RAID 5 NAS Calculator | Usable TB →

FAQ

Why include a 10% reserve when planning NAS storage headroom?

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

Is RAID 1 still practical with 10TB drives?

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

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.

How much usable storage does 12x 10TB RAID 1 provide?

This NAS planning scenario estimates 9.00 TB usable after a 10% reserve from 120.00 TB raw.