UK 4x 8TB RAID-Z1 NAS Calculator

Estimate usable TB, parity, and fault tolerance for UK homelab buyers using 4x 8TB in RAID-Z1.

Capacity Snapshot

Raw Capacity

32.00 TB

Usable Capacity

21.60 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	21.60 TB	1 drive	75.0%
RAID 6	14.40 TB	2 drives	50.0%
RAID 10	14.40 TB	1 drive per mirror pair*	50.0%
RAID-Z1	21.60 TB	1 drive	75.0%
RAID-Z2	14.40 TB	2 drives	50.0%

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

Related Long-Tail Calculators

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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 4x 8TB RAID-Z1 provide?

For UK homelab buyers, this NAS planning scenario estimates 21.60 TB usable after a 10% reserve from 32.00 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.

Should I optimize this 4-drive plan for storage headroom 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.