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RAID-Z3 vs RAID-Z2 Storage Capacity Calculator

Compare usable capacity, fault tolerance, and efficiency between RAID-Z3 and RAID-Z2 for NAS and homelab arrays.

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
Open Interactive Planner →

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

Related Long-Tail Calculators

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

FAQ

Which has more real-world usable available space: RAID-Z3 or RAID-Z2?

This NAS planning scenario compares both modes at fixed drive sizes so you can see usable capacity differences before buying disks.

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 storage headroom still have very different failure exposure?

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

How should I pick between RAID-Z3 and RAID-Z2?

Choose based on your risk tolerance, rebuild window, and performance profile. Higher parity usually lowers capacity but improves resilience.