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12x 12TB RAID 5 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 12x 12TB in RAID 5. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

144.00 TB

Usable Capacity

118.80 TB

Fault Tolerance

1 drive

Efficiency

91.7%

Balanced capacity and redundancy, but rebuild stress can be high on large disks. This scenario applies a 10% filesystem reserve.

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Alternative Mode Comparison

Mode Usable Tolerance Efficiency
RAID 5 118.80 TB 1 drive 91.7%
RAID 6 108.00 TB 2 drives 83.3%
RAID 10 64.80 TB 1 drive per mirror pair* 50.0%
RAID-Z1 118.80 TB 1 drive 91.7%
RAID-Z2 108.00 TB 2 drives 83.3%

NAS Cluster Guides

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

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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 12TB RAID 1 NAS Calculator | Usable TB Next: 12x 12TB RAID 6 NAS Calculator | Usable TB →

FAQ

How many disk failures can RAID 5 tolerate in this setup?

This setup can tolerate 1 drive. Real-world survivability depends on mirror placement, rebuild stress, and drive health.

Is RAID 5 still viable 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.

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 capacity?

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