UK 10x 12TB RAID-Z2 NAS Calculator

Estimate usable TB, parity, and fault tolerance for UK homelab buyers using 10x 12TB in RAID-Z2.

Capacity Snapshot

Raw Capacity

120.00 TB

Usable Capacity

86.40 TB

Fault Tolerance

2 drives

Efficiency

80.0%

Popular TrueNAS default for medium arrays; dual-parity with good safety margin. This scenario applies a 10% filesystem reserve.

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Alternative Mode Comparison

Mode	Usable	Tolerance	Efficiency
RAID 5	97.20 TB	1 drive	90.0%
RAID 6	86.40 TB	2 drives	80.0%
RAID 10	54.00 TB	1 drive per mirror pair*	50.0%
RAID-Z1	97.20 TB	1 drive	90.0%
RAID-Z2	86.40 TB	2 drives	80.0%

UK Buyer Context

UK homelab planners commonly balance higher per-drive pricing with power and chassis constraints, so efficient but resilient layouts become more valuable.

• Model dual-parity options early if rebuild time is a concern.
• Include reserve headroom to avoid running pools at high fill percentages.

Brand / Region Glossary

Power Budget

Expected always-on energy usage cost factored into NAS layout decisions.

Rebuild Window

Estimated time exposure while replacing a failed drive and restoring parity.

NAS Cluster Guides

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

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Sequential Long-Tail Navigation

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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.

How much real-world usable storage does 10x 12TB RAID-Z2 provide?

For UK homelab buyers, this NAS planning scenario estimates 86.40 TB usable after a 10% reserve from 120.00 TB raw.

How many disk failures can RAID-Z2 tolerate in this setup?

This setup can tolerate 2 drives. Real-world survivability depends on mirror placement, rebuild stress, and drive health.

Is RAID-Z2 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.