EU 4x 12TB RAID-Z1 NAS Calculator

Estimate usable TB, parity, and fault tolerance for EU homelab buyers using 4x 12TB in RAID-Z1.

Capacity Snapshot

Raw Capacity

48.00 TB

Usable Capacity

32.40 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	32.40 TB	1 drive	75.0%
RAID 6	21.60 TB	2 drives	50.0%
RAID 10	21.60 TB	1 drive per mirror pair*	50.0%
RAID-Z1	32.40 TB	1 drive	75.0%
RAID-Z2	21.60 TB	2 drives	50.0%

EU Buyer Context

EU deployments often place additional emphasis on energy efficiency and predictable lifecycle upgrades, especially for always-on NAS fleets.

• Choose a layout that minimizes emergency rebuild risk under continuous operation.
• Prefer capacity plans that survive one upgrade cycle without pool redesign.

Brand / Region Glossary

Lifecycle Planning

Capacity and reliability strategy across multiple hardware refresh cycles.

Operational Headroom

Intentional free-space margin to protect performance and snapshot behavior.

NAS Cluster Guides

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

Related Long-Tail Calculators

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Sequential Long-Tail Navigation

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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.

Is RAID-Z1 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.

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.

How many disk failures can RAID-Z1 tolerate in this setup?

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