UK RAID-Z3 vs RAID-Z2 Calculator

Compare usable TB, parity, and failure tolerance between RAID-Z3 and RAID-Z2 for UK homelab setups.

Planning route

Answer the capacity question, then validate the purchase path

Use this worked example as a numeric starting point, then validate the RAID choice, capacity reserve, hardware plan, and backup path.

Decision aid RAID level selector Reference Capacity matrix

Editorial method

What this calculator can—and cannot—decide

The capacity model makes drive count, drive size, RAID layout, and reserve visible. It is a planning aid: it does not predict exact performance, rebuild duration, hardware compatibility, or the probability of data loss for a specific system.

Last reviewed: July 10, 2026. Product links remain neutral category searches until a partner relationship and page-level disclosure are in place.

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Comparison Notes

This page compares RAID-Z3 and RAID-Z2 on identical hardware assumptions to help homelab builders choose between capacity efficiency and fault tolerance.

Disk size baseline: 8TB drives
Reserve policy: 10% filesystem headroom
Use the interactive tool for exact real-world constraints

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Storage Capacity Table

Drives	RAID-Z3	RAID-Z2	Delta
4x 8TB	N/A	14.40 TB	N/A
6x 8TB	21.60 TB	28.80 TB	-7.20 TB
8x 8TB	36.00 TB	43.20 TB	-7.20 TB
10x 8TB	50.40 TB	57.60 TB	-7.20 TB
12x 8TB	64.80 TB	72.00 TB	-7.20 TB

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.

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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 navigation

Move through the storage decision path

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NAS Hub Calculator and buying path Learning Center 8-step guide path RAID Comparison Mode-by-mode matrix RAID Selector Choose by priority Capacity Matrix Citation-ready reference NAS FAQ Planning answers

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Sequential long-tail navigation

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FAQ

Which option is usually better for long-term homelab growth?

The better option is the one that keeps acceptable usable capacity while preserving safety margins during future disk expansions.

Does RAID-Z3 rebuild faster than RAID-Z2?

Rebuild behavior depends on array width, disk size, and workload pressure. This page focuses on capacity and tolerance; benchmark your actual platform before final choice.

Does this comparison include filesystem reserve?

Yes. The comparison table applies a 10% reserve baseline to reflect realistic operating headroom in NAS and homelab environments.

Can two layouts with similar capacity still have very different risk?

Yes. Similar usable TB does not imply similar failure tolerance or rebuild exposure. Capacity and resiliency should be evaluated together.